August 2024 - Linux-stable-mirror

FAILED: patch "[PATCH] btrfs: check delayed refs when we're checking if a ref exists" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 42fac187b5c746227c92d024f1caf33bc1d337e4 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024081933-lyricism-manly-3272@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: 42fac187b5c7 ("btrfs: check delayed refs when we're checking if a ref exists") e094f48040cd ("btrfs: change root->root_key.objectid to btrfs_root_id()") 44cc2e38e67b ("btrfs: stop referencing btrfs_delayed_data_ref directly") cf4f04325b2b ("btrfs: move ->parent and ->ref_root into btrfs_delayed_ref_node") 12390e42b69d ("btrfs: rename ->len to ->num_bytes in btrfs_ref") 1bff6d4f8737 ("btrfs: simplify delayed ref tracepoints") 0ea4703cc27e ("btrfs: move ref specific initialization into init_delayed_ref_common") 0509cc56619d ("btrfs: initialize btrfs_delayed_ref_head with btrfs_ref") da3c54854197 ("btrfs: pass btrfs_ref to init_delayed_ref_common") f2e69a77aa51 ("btrfs: move ref_root into btrfs_ref") 4d09b4e942bc ("btrfs: do not use a function to initialize btrfs_ref") d3fbb00f5e21 ("btrfs: embed data_ref and tree_ref in btrfs_delayed_ref_node") 0eea355fc0f4 ("btrfs: add a helper to get the delayed ref node from the data/tree ref") 6de3595473b0 ("btrfs: compression: add error handling for missed page cache") 01b69bf9906b ("btrfs: convert put_file_data() to folios") 073bda7a5417 ("btrfs: zoned: add ASSERT and WARN for EXTENT_BUFFER_ZONED_ZEROOUT handling") 141fb8cd206a ("btrfs: qgroup: correctly model root qgroup rsv in convert") ef5a05c55704 ("btrfs: remove SLAB_MEM_SPREAD flag use") 06c9564980f1 ("btrfs: use KMEM_CACHE() to create btrfs_free_space cache") b2c7d55e4c4c ("btrfs: use KMEM_CACHE() to create delayed ref caches") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 42fac187b5c746227c92d024f1caf33bc1d337e4 Mon Sep 17 00:00:00 2001 From: Josef Bacik <josef(a)toxicpanda.com> Date: Thu, 11 Apr 2024 16:41:20 -0400 Subject: [PATCH] btrfs: check delayed refs when we're checking if a ref exists In the patch 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") I added some code to handle file systems that had been corrupted by a bug that incorrectly skipped updating the drop progress key while dropping a snapshot. This code would check to see if we had already deleted our reference for a child block, and skip the deletion if we had already. Unfortunately there is a bug, as the check would only check the on-disk references. I made an incorrect assumption that blocks in an already deleted snapshot that was having the deletion resume on mount wouldn't be modified. If we have 2 pending deleted snapshots that share blocks, we can easily modify the rules for a block. Take the following example subvolume a exists, and subvolume b is a snapshot of subvolume a. They share references to block 1. Block 1 will have 2 full references, one for subvolume a and one for subvolume b, and it belongs to subvolume a (btrfs_header_owner(block 1) == subvolume a). When deleting subvolume a, we will drop our full reference for block 1, and because we are the owner we will drop our full reference for all of block 1's children, convert block 1 to FULL BACKREF, and add a shared reference to all of block 1's children. Then we will start the snapshot deletion of subvolume b. We look up the extent info for block 1, which checks delayed refs and tells us that FULL BACKREF is set, so sets parent to the bytenr of block 1. However because this is a resumed snapshot deletion, we call into check_ref_exists(). Because check_ref_exists() only looks at the disk, it doesn't find the shared backref for the child of block 1, and thus returns 0 and we skip deleting the reference for the child of block 1 and continue. This orphans the child of block 1. The fix is to lookup the delayed refs, similar to what we do in btrfs_lookup_extent_info(). However we only care about whether the reference exists or not. If we fail to find our reference on disk, go look up the bytenr in the delayed refs, and if it exists look for an existing ref in the delayed ref head. If that exists then we know we can delete the reference safely and carry on. If it doesn't exist we know we have to skip over this block. This bug has existed since I introduced this fix, however requires having multiple deleted snapshots pending when we unmount. We noticed this in production because our shutdown path stops the container on the system, which deletes a bunch of subvolumes, and then reboots the box. This gives us plenty of opportunities to hit this issue. Looking at the history we've seen this occasionally in production, but we had a big spike recently thanks to faster machines getting jobs with multiple subvolumes in the job. Chris Mason wrote a reproducer which does the following mount /dev/nvme4n1 /btrfs btrfs subvol create /btrfs/s1 simoop -E -f 4k -n 200000 -z /btrfs/s1 while(true) ; do btrfs subvol snap /btrfs/s1 /btrfs/s2 simoop -f 4k -n 200000 -r 10 -z /btrfs/s2 btrfs subvol snap /btrfs/s2 /btrfs/s3 btrfs balance start -dusage=80 /btrfs btrfs subvol del /btrfs/s2 /btrfs/s3 umount /btrfs btrfsck /dev/nvme4n1 || exit 1 mount /dev/nvme4n1 /btrfs done On the second loop this would fail consistently, with my patch it has been running for hours and hasn't failed. I also used dm-log-writes to capture the state of the failure so I could debug the problem. Using the existing failure case to test my patch validated that it fixes the problem. Fixes: 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") CC: stable(a)vger.kernel.org # 5.4+ Reviewed-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 2ac9296edccb..06a9e0542d70 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -1134,6 +1134,73 @@ btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs, u64 byt return find_ref_head(delayed_refs, bytenr, false); } +static int find_comp(struct btrfs_delayed_ref_node *entry, u64 root, u64 parent) +{ + int type = parent ? BTRFS_SHARED_BLOCK_REF_KEY : BTRFS_TREE_BLOCK_REF_KEY; + + if (type < entry->type) + return -1; + if (type > entry->type) + return 1; + + if (type == BTRFS_TREE_BLOCK_REF_KEY) { + if (root < entry->ref_root) + return -1; + if (root > entry->ref_root) + return 1; + } else { + if (parent < entry->parent) + return -1; + if (parent > entry->parent) + return 1; + } + return 0; +} + +/* + * Check to see if a given root/parent reference is attached to the head. This + * only checks for BTRFS_ADD_DELAYED_REF references that match, as that + * indicates the reference exists for the given root or parent. This is for + * tree blocks only. + * + * @head: the head of the bytenr we're searching. + * @root: the root objectid of the reference if it is a normal reference. + * @parent: the parent if this is a shared backref. + */ +bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head, + u64 root, u64 parent) +{ + struct rb_node *node; + bool found = false; + + lockdep_assert_held(&head->mutex); + + spin_lock(&head->lock); + node = head->ref_tree.rb_root.rb_node; + while (node) { + struct btrfs_delayed_ref_node *entry; + int ret; + + entry = rb_entry(node, struct btrfs_delayed_ref_node, ref_node); + ret = find_comp(entry, root, parent); + if (ret < 0) { + node = node->rb_left; + } else if (ret > 0) { + node = node->rb_right; + } else { + /* + * We only want to count ADD actions, as drops mean the + * ref doesn't exist. + */ + if (entry->action == BTRFS_ADD_DELAYED_REF) + found = true; + break; + } + } + spin_unlock(&head->lock); + return found; +} + void __cold btrfs_delayed_ref_exit(void) { kmem_cache_destroy(btrfs_delayed_ref_head_cachep); diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index ef15e998be03..05f634eb472d 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -389,6 +389,8 @@ void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info); int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info, enum btrfs_reserve_flush_enum flush); bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info); +bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head, + u64 root, u64 parent); static inline u64 btrfs_delayed_ref_owner(struct btrfs_delayed_ref_node *node) { diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index ff9f0d41987e..feec49e6f9c8 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5472,23 +5472,62 @@ static int check_ref_exists(struct btrfs_trans_handle *trans, struct btrfs_root *root, u64 bytenr, u64 parent, int level) { + struct btrfs_delayed_ref_root *delayed_refs; + struct btrfs_delayed_ref_head *head; struct btrfs_path *path; struct btrfs_extent_inline_ref *iref; int ret; + bool exists = false; path = btrfs_alloc_path(); if (!path) return -ENOMEM; - +again: ret = lookup_extent_backref(trans, path, &iref, bytenr, root->fs_info->nodesize, parent, btrfs_root_id(root), level, 0); + if (ret != -ENOENT) { + /* + * If we get 0 then we found our reference, return 1, else + * return the error if it's not -ENOENT; + */ + btrfs_free_path(path); + return (ret < 0 ) ? ret : 1; + } + + /* + * We could have a delayed ref with this reference, so look it up while + * we're holding the path open to make sure we don't race with the + * delayed ref running. + */ + delayed_refs = &trans->transaction->delayed_refs; + spin_lock(&delayed_refs->lock); + head = btrfs_find_delayed_ref_head(delayed_refs, bytenr); + if (!head) + goto out; + if (!mutex_trylock(&head->mutex)) { + /* + * We're contended, means that the delayed ref is running, get a + * reference and wait for the ref head to be complete and then + * try again. + */ + refcount_inc(&head->refs); + spin_unlock(&delayed_refs->lock); + + btrfs_release_path(path); + + mutex_lock(&head->mutex); + mutex_unlock(&head->mutex); + btrfs_put_delayed_ref_head(head); + goto again; + } + + exists = btrfs_find_delayed_tree_ref(head, root->root_key.objectid, parent); + mutex_unlock(&head->mutex); +out: + spin_unlock(&delayed_refs->lock); btrfs_free_path(path); - if (ret == -ENOENT) - return 0; - if (ret < 0) - return ret; - return 1; + return exists ? 1 : 0; } /*

4 months, 3 weeks

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FAILED: patch "[PATCH] btrfs: check delayed refs when we're checking if a ref exists" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 42fac187b5c746227c92d024f1caf33bc1d337e4 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024081931-slot-improving-a44a@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: 42fac187b5c7 ("btrfs: check delayed refs when we're checking if a ref exists") e094f48040cd ("btrfs: change root->root_key.objectid to btrfs_root_id()") 44cc2e38e67b ("btrfs: stop referencing btrfs_delayed_data_ref directly") cf4f04325b2b ("btrfs: move ->parent and ->ref_root into btrfs_delayed_ref_node") 12390e42b69d ("btrfs: rename ->len to ->num_bytes in btrfs_ref") 1bff6d4f8737 ("btrfs: simplify delayed ref tracepoints") 0ea4703cc27e ("btrfs: move ref specific initialization into init_delayed_ref_common") 0509cc56619d ("btrfs: initialize btrfs_delayed_ref_head with btrfs_ref") da3c54854197 ("btrfs: pass btrfs_ref to init_delayed_ref_common") f2e69a77aa51 ("btrfs: move ref_root into btrfs_ref") 4d09b4e942bc ("btrfs: do not use a function to initialize btrfs_ref") d3fbb00f5e21 ("btrfs: embed data_ref and tree_ref in btrfs_delayed_ref_node") 0eea355fc0f4 ("btrfs: add a helper to get the delayed ref node from the data/tree ref") 6de3595473b0 ("btrfs: compression: add error handling for missed page cache") 01b69bf9906b ("btrfs: convert put_file_data() to folios") 073bda7a5417 ("btrfs: zoned: add ASSERT and WARN for EXTENT_BUFFER_ZONED_ZEROOUT handling") 141fb8cd206a ("btrfs: qgroup: correctly model root qgroup rsv in convert") ef5a05c55704 ("btrfs: remove SLAB_MEM_SPREAD flag use") 06c9564980f1 ("btrfs: use KMEM_CACHE() to create btrfs_free_space cache") b2c7d55e4c4c ("btrfs: use KMEM_CACHE() to create delayed ref caches") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 42fac187b5c746227c92d024f1caf33bc1d337e4 Mon Sep 17 00:00:00 2001 From: Josef Bacik <josef(a)toxicpanda.com> Date: Thu, 11 Apr 2024 16:41:20 -0400 Subject: [PATCH] btrfs: check delayed refs when we're checking if a ref exists In the patch 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") I added some code to handle file systems that had been corrupted by a bug that incorrectly skipped updating the drop progress key while dropping a snapshot. This code would check to see if we had already deleted our reference for a child block, and skip the deletion if we had already. Unfortunately there is a bug, as the check would only check the on-disk references. I made an incorrect assumption that blocks in an already deleted snapshot that was having the deletion resume on mount wouldn't be modified. If we have 2 pending deleted snapshots that share blocks, we can easily modify the rules for a block. Take the following example subvolume a exists, and subvolume b is a snapshot of subvolume a. They share references to block 1. Block 1 will have 2 full references, one for subvolume a and one for subvolume b, and it belongs to subvolume a (btrfs_header_owner(block 1) == subvolume a). When deleting subvolume a, we will drop our full reference for block 1, and because we are the owner we will drop our full reference for all of block 1's children, convert block 1 to FULL BACKREF, and add a shared reference to all of block 1's children. Then we will start the snapshot deletion of subvolume b. We look up the extent info for block 1, which checks delayed refs and tells us that FULL BACKREF is set, so sets parent to the bytenr of block 1. However because this is a resumed snapshot deletion, we call into check_ref_exists(). Because check_ref_exists() only looks at the disk, it doesn't find the shared backref for the child of block 1, and thus returns 0 and we skip deleting the reference for the child of block 1 and continue. This orphans the child of block 1. The fix is to lookup the delayed refs, similar to what we do in btrfs_lookup_extent_info(). However we only care about whether the reference exists or not. If we fail to find our reference on disk, go look up the bytenr in the delayed refs, and if it exists look for an existing ref in the delayed ref head. If that exists then we know we can delete the reference safely and carry on. If it doesn't exist we know we have to skip over this block. This bug has existed since I introduced this fix, however requires having multiple deleted snapshots pending when we unmount. We noticed this in production because our shutdown path stops the container on the system, which deletes a bunch of subvolumes, and then reboots the box. This gives us plenty of opportunities to hit this issue. Looking at the history we've seen this occasionally in production, but we had a big spike recently thanks to faster machines getting jobs with multiple subvolumes in the job. Chris Mason wrote a reproducer which does the following mount /dev/nvme4n1 /btrfs btrfs subvol create /btrfs/s1 simoop -E -f 4k -n 200000 -z /btrfs/s1 while(true) ; do btrfs subvol snap /btrfs/s1 /btrfs/s2 simoop -f 4k -n 200000 -r 10 -z /btrfs/s2 btrfs subvol snap /btrfs/s2 /btrfs/s3 btrfs balance start -dusage=80 /btrfs btrfs subvol del /btrfs/s2 /btrfs/s3 umount /btrfs btrfsck /dev/nvme4n1 || exit 1 mount /dev/nvme4n1 /btrfs done On the second loop this would fail consistently, with my patch it has been running for hours and hasn't failed. I also used dm-log-writes to capture the state of the failure so I could debug the problem. Using the existing failure case to test my patch validated that it fixes the problem. Fixes: 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") CC: stable(a)vger.kernel.org # 5.4+ Reviewed-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 2ac9296edccb..06a9e0542d70 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -1134,6 +1134,73 @@ btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs, u64 byt return find_ref_head(delayed_refs, bytenr, false); } +static int find_comp(struct btrfs_delayed_ref_node *entry, u64 root, u64 parent) +{ + int type = parent ? BTRFS_SHARED_BLOCK_REF_KEY : BTRFS_TREE_BLOCK_REF_KEY; + + if (type < entry->type) + return -1; + if (type > entry->type) + return 1; + + if (type == BTRFS_TREE_BLOCK_REF_KEY) { + if (root < entry->ref_root) + return -1; + if (root > entry->ref_root) + return 1; + } else { + if (parent < entry->parent) + return -1; + if (parent > entry->parent) + return 1; + } + return 0; +} + +/* + * Check to see if a given root/parent reference is attached to the head. This + * only checks for BTRFS_ADD_DELAYED_REF references that match, as that + * indicates the reference exists for the given root or parent. This is for + * tree blocks only. + * + * @head: the head of the bytenr we're searching. + * @root: the root objectid of the reference if it is a normal reference. + * @parent: the parent if this is a shared backref. + */ +bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head, + u64 root, u64 parent) +{ + struct rb_node *node; + bool found = false; + + lockdep_assert_held(&head->mutex); + + spin_lock(&head->lock); + node = head->ref_tree.rb_root.rb_node; + while (node) { + struct btrfs_delayed_ref_node *entry; + int ret; + + entry = rb_entry(node, struct btrfs_delayed_ref_node, ref_node); + ret = find_comp(entry, root, parent); + if (ret < 0) { + node = node->rb_left; + } else if (ret > 0) { + node = node->rb_right; + } else { + /* + * We only want to count ADD actions, as drops mean the + * ref doesn't exist. + */ + if (entry->action == BTRFS_ADD_DELAYED_REF) + found = true; + break; + } + } + spin_unlock(&head->lock); + return found; +} + void __cold btrfs_delayed_ref_exit(void) { kmem_cache_destroy(btrfs_delayed_ref_head_cachep); diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index ef15e998be03..05f634eb472d 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -389,6 +389,8 @@ void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info); int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info, enum btrfs_reserve_flush_enum flush); bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info); +bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head, + u64 root, u64 parent); static inline u64 btrfs_delayed_ref_owner(struct btrfs_delayed_ref_node *node) { diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index ff9f0d41987e..feec49e6f9c8 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5472,23 +5472,62 @@ static int check_ref_exists(struct btrfs_trans_handle *trans, struct btrfs_root *root, u64 bytenr, u64 parent, int level) { + struct btrfs_delayed_ref_root *delayed_refs; + struct btrfs_delayed_ref_head *head; struct btrfs_path *path; struct btrfs_extent_inline_ref *iref; int ret; + bool exists = false; path = btrfs_alloc_path(); if (!path) return -ENOMEM; - +again: ret = lookup_extent_backref(trans, path, &iref, bytenr, root->fs_info->nodesize, parent, btrfs_root_id(root), level, 0); + if (ret != -ENOENT) { + /* + * If we get 0 then we found our reference, return 1, else + * return the error if it's not -ENOENT; + */ + btrfs_free_path(path); + return (ret < 0 ) ? ret : 1; + } + + /* + * We could have a delayed ref with this reference, so look it up while + * we're holding the path open to make sure we don't race with the + * delayed ref running. + */ + delayed_refs = &trans->transaction->delayed_refs; + spin_lock(&delayed_refs->lock); + head = btrfs_find_delayed_ref_head(delayed_refs, bytenr); + if (!head) + goto out; + if (!mutex_trylock(&head->mutex)) { + /* + * We're contended, means that the delayed ref is running, get a + * reference and wait for the ref head to be complete and then + * try again. + */ + refcount_inc(&head->refs); + spin_unlock(&delayed_refs->lock); + + btrfs_release_path(path); + + mutex_lock(&head->mutex); + mutex_unlock(&head->mutex); + btrfs_put_delayed_ref_head(head); + goto again; + } + + exists = btrfs_find_delayed_tree_ref(head, root->root_key.objectid, parent); + mutex_unlock(&head->mutex); +out: + spin_unlock(&delayed_refs->lock); btrfs_free_path(path); - if (ret == -ENOENT) - return 0; - if (ret < 0) - return ret; - return 1; + return exists ? 1 : 0; } /*

4 months, 3 weeks

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FAILED: patch "[PATCH] btrfs: check delayed refs when we're checking if a ref exists" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 42fac187b5c746227c92d024f1caf33bc1d337e4 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024081929-drastic-shale-7639@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: 42fac187b5c7 ("btrfs: check delayed refs when we're checking if a ref exists") e094f48040cd ("btrfs: change root->root_key.objectid to btrfs_root_id()") 44cc2e38e67b ("btrfs: stop referencing btrfs_delayed_data_ref directly") cf4f04325b2b ("btrfs: move ->parent and ->ref_root into btrfs_delayed_ref_node") 12390e42b69d ("btrfs: rename ->len to ->num_bytes in btrfs_ref") 1bff6d4f8737 ("btrfs: simplify delayed ref tracepoints") 0ea4703cc27e ("btrfs: move ref specific initialization into init_delayed_ref_common") 0509cc56619d ("btrfs: initialize btrfs_delayed_ref_head with btrfs_ref") da3c54854197 ("btrfs: pass btrfs_ref to init_delayed_ref_common") f2e69a77aa51 ("btrfs: move ref_root into btrfs_ref") 4d09b4e942bc ("btrfs: do not use a function to initialize btrfs_ref") d3fbb00f5e21 ("btrfs: embed data_ref and tree_ref in btrfs_delayed_ref_node") 0eea355fc0f4 ("btrfs: add a helper to get the delayed ref node from the data/tree ref") 6de3595473b0 ("btrfs: compression: add error handling for missed page cache") 01b69bf9906b ("btrfs: convert put_file_data() to folios") 073bda7a5417 ("btrfs: zoned: add ASSERT and WARN for EXTENT_BUFFER_ZONED_ZEROOUT handling") 141fb8cd206a ("btrfs: qgroup: correctly model root qgroup rsv in convert") ef5a05c55704 ("btrfs: remove SLAB_MEM_SPREAD flag use") 06c9564980f1 ("btrfs: use KMEM_CACHE() to create btrfs_free_space cache") b2c7d55e4c4c ("btrfs: use KMEM_CACHE() to create delayed ref caches") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 42fac187b5c746227c92d024f1caf33bc1d337e4 Mon Sep 17 00:00:00 2001 From: Josef Bacik <josef(a)toxicpanda.com> Date: Thu, 11 Apr 2024 16:41:20 -0400 Subject: [PATCH] btrfs: check delayed refs when we're checking if a ref exists In the patch 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") I added some code to handle file systems that had been corrupted by a bug that incorrectly skipped updating the drop progress key while dropping a snapshot. This code would check to see if we had already deleted our reference for a child block, and skip the deletion if we had already. Unfortunately there is a bug, as the check would only check the on-disk references. I made an incorrect assumption that blocks in an already deleted snapshot that was having the deletion resume on mount wouldn't be modified. If we have 2 pending deleted snapshots that share blocks, we can easily modify the rules for a block. Take the following example subvolume a exists, and subvolume b is a snapshot of subvolume a. They share references to block 1. Block 1 will have 2 full references, one for subvolume a and one for subvolume b, and it belongs to subvolume a (btrfs_header_owner(block 1) == subvolume a). When deleting subvolume a, we will drop our full reference for block 1, and because we are the owner we will drop our full reference for all of block 1's children, convert block 1 to FULL BACKREF, and add a shared reference to all of block 1's children. Then we will start the snapshot deletion of subvolume b. We look up the extent info for block 1, which checks delayed refs and tells us that FULL BACKREF is set, so sets parent to the bytenr of block 1. However because this is a resumed snapshot deletion, we call into check_ref_exists(). Because check_ref_exists() only looks at the disk, it doesn't find the shared backref for the child of block 1, and thus returns 0 and we skip deleting the reference for the child of block 1 and continue. This orphans the child of block 1. The fix is to lookup the delayed refs, similar to what we do in btrfs_lookup_extent_info(). However we only care about whether the reference exists or not. If we fail to find our reference on disk, go look up the bytenr in the delayed refs, and if it exists look for an existing ref in the delayed ref head. If that exists then we know we can delete the reference safely and carry on. If it doesn't exist we know we have to skip over this block. This bug has existed since I introduced this fix, however requires having multiple deleted snapshots pending when we unmount. We noticed this in production because our shutdown path stops the container on the system, which deletes a bunch of subvolumes, and then reboots the box. This gives us plenty of opportunities to hit this issue. Looking at the history we've seen this occasionally in production, but we had a big spike recently thanks to faster machines getting jobs with multiple subvolumes in the job. Chris Mason wrote a reproducer which does the following mount /dev/nvme4n1 /btrfs btrfs subvol create /btrfs/s1 simoop -E -f 4k -n 200000 -z /btrfs/s1 while(true) ; do btrfs subvol snap /btrfs/s1 /btrfs/s2 simoop -f 4k -n 200000 -r 10 -z /btrfs/s2 btrfs subvol snap /btrfs/s2 /btrfs/s3 btrfs balance start -dusage=80 /btrfs btrfs subvol del /btrfs/s2 /btrfs/s3 umount /btrfs btrfsck /dev/nvme4n1 || exit 1 mount /dev/nvme4n1 /btrfs done On the second loop this would fail consistently, with my patch it has been running for hours and hasn't failed. I also used dm-log-writes to capture the state of the failure so I could debug the problem. Using the existing failure case to test my patch validated that it fixes the problem. Fixes: 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") CC: stable(a)vger.kernel.org # 5.4+ Reviewed-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 2ac9296edccb..06a9e0542d70 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -1134,6 +1134,73 @@ btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs, u64 byt return find_ref_head(delayed_refs, bytenr, false); } +static int find_comp(struct btrfs_delayed_ref_node *entry, u64 root, u64 parent) +{ + int type = parent ? BTRFS_SHARED_BLOCK_REF_KEY : BTRFS_TREE_BLOCK_REF_KEY; + + if (type < entry->type) + return -1; + if (type > entry->type) + return 1; + + if (type == BTRFS_TREE_BLOCK_REF_KEY) { + if (root < entry->ref_root) + return -1; + if (root > entry->ref_root) + return 1; + } else { + if (parent < entry->parent) + return -1; + if (parent > entry->parent) + return 1; + } + return 0; +} + +/* + * Check to see if a given root/parent reference is attached to the head. This + * only checks for BTRFS_ADD_DELAYED_REF references that match, as that + * indicates the reference exists for the given root or parent. This is for + * tree blocks only. + * + * @head: the head of the bytenr we're searching. + * @root: the root objectid of the reference if it is a normal reference. + * @parent: the parent if this is a shared backref. + */ +bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head, + u64 root, u64 parent) +{ + struct rb_node *node; + bool found = false; + + lockdep_assert_held(&head->mutex); + + spin_lock(&head->lock); + node = head->ref_tree.rb_root.rb_node; + while (node) { + struct btrfs_delayed_ref_node *entry; + int ret; + + entry = rb_entry(node, struct btrfs_delayed_ref_node, ref_node); + ret = find_comp(entry, root, parent); + if (ret < 0) { + node = node->rb_left; + } else if (ret > 0) { + node = node->rb_right; + } else { + /* + * We only want to count ADD actions, as drops mean the + * ref doesn't exist. + */ + if (entry->action == BTRFS_ADD_DELAYED_REF) + found = true; + break; + } + } + spin_unlock(&head->lock); + return found; +} + void __cold btrfs_delayed_ref_exit(void) { kmem_cache_destroy(btrfs_delayed_ref_head_cachep); diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index ef15e998be03..05f634eb472d 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -389,6 +389,8 @@ void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info); int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info, enum btrfs_reserve_flush_enum flush); bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info); +bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head, + u64 root, u64 parent); static inline u64 btrfs_delayed_ref_owner(struct btrfs_delayed_ref_node *node) { diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index ff9f0d41987e..feec49e6f9c8 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5472,23 +5472,62 @@ static int check_ref_exists(struct btrfs_trans_handle *trans, struct btrfs_root *root, u64 bytenr, u64 parent, int level) { + struct btrfs_delayed_ref_root *delayed_refs; + struct btrfs_delayed_ref_head *head; struct btrfs_path *path; struct btrfs_extent_inline_ref *iref; int ret; + bool exists = false; path = btrfs_alloc_path(); if (!path) return -ENOMEM; - +again: ret = lookup_extent_backref(trans, path, &iref, bytenr, root->fs_info->nodesize, parent, btrfs_root_id(root), level, 0); + if (ret != -ENOENT) { + /* + * If we get 0 then we found our reference, return 1, else + * return the error if it's not -ENOENT; + */ + btrfs_free_path(path); + return (ret < 0 ) ? ret : 1; + } + + /* + * We could have a delayed ref with this reference, so look it up while + * we're holding the path open to make sure we don't race with the + * delayed ref running. + */ + delayed_refs = &trans->transaction->delayed_refs; + spin_lock(&delayed_refs->lock); + head = btrfs_find_delayed_ref_head(delayed_refs, bytenr); + if (!head) + goto out; + if (!mutex_trylock(&head->mutex)) { + /* + * We're contended, means that the delayed ref is running, get a + * reference and wait for the ref head to be complete and then + * try again. + */ + refcount_inc(&head->refs); + spin_unlock(&delayed_refs->lock); + + btrfs_release_path(path); + + mutex_lock(&head->mutex); + mutex_unlock(&head->mutex); + btrfs_put_delayed_ref_head(head); + goto again; + } + + exists = btrfs_find_delayed_tree_ref(head, root->root_key.objectid, parent); + mutex_unlock(&head->mutex); +out: + spin_unlock(&delayed_refs->lock); btrfs_free_path(path); - if (ret == -ENOENT) - return 0; - if (ret < 0) - return ret; - return 1; + return exists ? 1 : 0; } /*

4 months, 3 weeks

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FAILED: patch "[PATCH] btrfs: check delayed refs when we're checking if a ref exists" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 42fac187b5c746227c92d024f1caf33bc1d337e4 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024081927-overstay-bullseye-eee1@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: 42fac187b5c7 ("btrfs: check delayed refs when we're checking if a ref exists") e094f48040cd ("btrfs: change root->root_key.objectid to btrfs_root_id()") 44cc2e38e67b ("btrfs: stop referencing btrfs_delayed_data_ref directly") cf4f04325b2b ("btrfs: move ->parent and ->ref_root into btrfs_delayed_ref_node") 12390e42b69d ("btrfs: rename ->len to ->num_bytes in btrfs_ref") 1bff6d4f8737 ("btrfs: simplify delayed ref tracepoints") 0ea4703cc27e ("btrfs: move ref specific initialization into init_delayed_ref_common") 0509cc56619d ("btrfs: initialize btrfs_delayed_ref_head with btrfs_ref") da3c54854197 ("btrfs: pass btrfs_ref to init_delayed_ref_common") f2e69a77aa51 ("btrfs: move ref_root into btrfs_ref") 4d09b4e942bc ("btrfs: do not use a function to initialize btrfs_ref") d3fbb00f5e21 ("btrfs: embed data_ref and tree_ref in btrfs_delayed_ref_node") 0eea355fc0f4 ("btrfs: add a helper to get the delayed ref node from the data/tree ref") 6de3595473b0 ("btrfs: compression: add error handling for missed page cache") 01b69bf9906b ("btrfs: convert put_file_data() to folios") 073bda7a5417 ("btrfs: zoned: add ASSERT and WARN for EXTENT_BUFFER_ZONED_ZEROOUT handling") 141fb8cd206a ("btrfs: qgroup: correctly model root qgroup rsv in convert") ef5a05c55704 ("btrfs: remove SLAB_MEM_SPREAD flag use") 06c9564980f1 ("btrfs: use KMEM_CACHE() to create btrfs_free_space cache") b2c7d55e4c4c ("btrfs: use KMEM_CACHE() to create delayed ref caches") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 42fac187b5c746227c92d024f1caf33bc1d337e4 Mon Sep 17 00:00:00 2001 From: Josef Bacik <josef(a)toxicpanda.com> Date: Thu, 11 Apr 2024 16:41:20 -0400 Subject: [PATCH] btrfs: check delayed refs when we're checking if a ref exists In the patch 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") I added some code to handle file systems that had been corrupted by a bug that incorrectly skipped updating the drop progress key while dropping a snapshot. This code would check to see if we had already deleted our reference for a child block, and skip the deletion if we had already. Unfortunately there is a bug, as the check would only check the on-disk references. I made an incorrect assumption that blocks in an already deleted snapshot that was having the deletion resume on mount wouldn't be modified. If we have 2 pending deleted snapshots that share blocks, we can easily modify the rules for a block. Take the following example subvolume a exists, and subvolume b is a snapshot of subvolume a. They share references to block 1. Block 1 will have 2 full references, one for subvolume a and one for subvolume b, and it belongs to subvolume a (btrfs_header_owner(block 1) == subvolume a). When deleting subvolume a, we will drop our full reference for block 1, and because we are the owner we will drop our full reference for all of block 1's children, convert block 1 to FULL BACKREF, and add a shared reference to all of block 1's children. Then we will start the snapshot deletion of subvolume b. We look up the extent info for block 1, which checks delayed refs and tells us that FULL BACKREF is set, so sets parent to the bytenr of block 1. However because this is a resumed snapshot deletion, we call into check_ref_exists(). Because check_ref_exists() only looks at the disk, it doesn't find the shared backref for the child of block 1, and thus returns 0 and we skip deleting the reference for the child of block 1 and continue. This orphans the child of block 1. The fix is to lookup the delayed refs, similar to what we do in btrfs_lookup_extent_info(). However we only care about whether the reference exists or not. If we fail to find our reference on disk, go look up the bytenr in the delayed refs, and if it exists look for an existing ref in the delayed ref head. If that exists then we know we can delete the reference safely and carry on. If it doesn't exist we know we have to skip over this block. This bug has existed since I introduced this fix, however requires having multiple deleted snapshots pending when we unmount. We noticed this in production because our shutdown path stops the container on the system, which deletes a bunch of subvolumes, and then reboots the box. This gives us plenty of opportunities to hit this issue. Looking at the history we've seen this occasionally in production, but we had a big spike recently thanks to faster machines getting jobs with multiple subvolumes in the job. Chris Mason wrote a reproducer which does the following mount /dev/nvme4n1 /btrfs btrfs subvol create /btrfs/s1 simoop -E -f 4k -n 200000 -z /btrfs/s1 while(true) ; do btrfs subvol snap /btrfs/s1 /btrfs/s2 simoop -f 4k -n 200000 -r 10 -z /btrfs/s2 btrfs subvol snap /btrfs/s2 /btrfs/s3 btrfs balance start -dusage=80 /btrfs btrfs subvol del /btrfs/s2 /btrfs/s3 umount /btrfs btrfsck /dev/nvme4n1 || exit 1 mount /dev/nvme4n1 /btrfs done On the second loop this would fail consistently, with my patch it has been running for hours and hasn't failed. I also used dm-log-writes to capture the state of the failure so I could debug the problem. Using the existing failure case to test my patch validated that it fixes the problem. Fixes: 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") CC: stable(a)vger.kernel.org # 5.4+ Reviewed-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 2ac9296edccb..06a9e0542d70 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -1134,6 +1134,73 @@ btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs, u64 byt return find_ref_head(delayed_refs, bytenr, false); } +static int find_comp(struct btrfs_delayed_ref_node *entry, u64 root, u64 parent) +{ + int type = parent ? BTRFS_SHARED_BLOCK_REF_KEY : BTRFS_TREE_BLOCK_REF_KEY; + + if (type < entry->type) + return -1; + if (type > entry->type) + return 1; + + if (type == BTRFS_TREE_BLOCK_REF_KEY) { + if (root < entry->ref_root) + return -1; + if (root > entry->ref_root) + return 1; + } else { + if (parent < entry->parent) + return -1; + if (parent > entry->parent) + return 1; + } + return 0; +} + +/* + * Check to see if a given root/parent reference is attached to the head. This + * only checks for BTRFS_ADD_DELAYED_REF references that match, as that + * indicates the reference exists for the given root or parent. This is for + * tree blocks only. + * + * @head: the head of the bytenr we're searching. + * @root: the root objectid of the reference if it is a normal reference. + * @parent: the parent if this is a shared backref. + */ +bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head, + u64 root, u64 parent) +{ + struct rb_node *node; + bool found = false; + + lockdep_assert_held(&head->mutex); + + spin_lock(&head->lock); + node = head->ref_tree.rb_root.rb_node; + while (node) { + struct btrfs_delayed_ref_node *entry; + int ret; + + entry = rb_entry(node, struct btrfs_delayed_ref_node, ref_node); + ret = find_comp(entry, root, parent); + if (ret < 0) { + node = node->rb_left; + } else if (ret > 0) { + node = node->rb_right; + } else { + /* + * We only want to count ADD actions, as drops mean the + * ref doesn't exist. + */ + if (entry->action == BTRFS_ADD_DELAYED_REF) + found = true; + break; + } + } + spin_unlock(&head->lock); + return found; +} + void __cold btrfs_delayed_ref_exit(void) { kmem_cache_destroy(btrfs_delayed_ref_head_cachep); diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index ef15e998be03..05f634eb472d 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -389,6 +389,8 @@ void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info); int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info, enum btrfs_reserve_flush_enum flush); bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info); +bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head, + u64 root, u64 parent); static inline u64 btrfs_delayed_ref_owner(struct btrfs_delayed_ref_node *node) { diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index ff9f0d41987e..feec49e6f9c8 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5472,23 +5472,62 @@ static int check_ref_exists(struct btrfs_trans_handle *trans, struct btrfs_root *root, u64 bytenr, u64 parent, int level) { + struct btrfs_delayed_ref_root *delayed_refs; + struct btrfs_delayed_ref_head *head; struct btrfs_path *path; struct btrfs_extent_inline_ref *iref; int ret; + bool exists = false; path = btrfs_alloc_path(); if (!path) return -ENOMEM; - +again: ret = lookup_extent_backref(trans, path, &iref, bytenr, root->fs_info->nodesize, parent, btrfs_root_id(root), level, 0); + if (ret != -ENOENT) { + /* + * If we get 0 then we found our reference, return 1, else + * return the error if it's not -ENOENT; + */ + btrfs_free_path(path); + return (ret < 0 ) ? ret : 1; + } + + /* + * We could have a delayed ref with this reference, so look it up while + * we're holding the path open to make sure we don't race with the + * delayed ref running. + */ + delayed_refs = &trans->transaction->delayed_refs; + spin_lock(&delayed_refs->lock); + head = btrfs_find_delayed_ref_head(delayed_refs, bytenr); + if (!head) + goto out; + if (!mutex_trylock(&head->mutex)) { + /* + * We're contended, means that the delayed ref is running, get a + * reference and wait for the ref head to be complete and then + * try again. + */ + refcount_inc(&head->refs); + spin_unlock(&delayed_refs->lock); + + btrfs_release_path(path); + + mutex_lock(&head->mutex); + mutex_unlock(&head->mutex); + btrfs_put_delayed_ref_head(head); + goto again; + } + + exists = btrfs_find_delayed_tree_ref(head, root->root_key.objectid, parent); + mutex_unlock(&head->mutex); +out: + spin_unlock(&delayed_refs->lock); btrfs_free_path(path); - if (ret == -ENOENT) - return 0; - if (ret < 0) - return ret; - return 1; + return exists ? 1 : 0; } /*

4 months, 3 weeks

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FAILED: patch "[PATCH] btrfs: check delayed refs when we're checking if a ref exists" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 42fac187b5c746227c92d024f1caf33bc1d337e4 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024081925-knoll-dropkick-f11a@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: 42fac187b5c7 ("btrfs: check delayed refs when we're checking if a ref exists") e094f48040cd ("btrfs: change root->root_key.objectid to btrfs_root_id()") 44cc2e38e67b ("btrfs: stop referencing btrfs_delayed_data_ref directly") cf4f04325b2b ("btrfs: move ->parent and ->ref_root into btrfs_delayed_ref_node") 12390e42b69d ("btrfs: rename ->len to ->num_bytes in btrfs_ref") 1bff6d4f8737 ("btrfs: simplify delayed ref tracepoints") 0ea4703cc27e ("btrfs: move ref specific initialization into init_delayed_ref_common") 0509cc56619d ("btrfs: initialize btrfs_delayed_ref_head with btrfs_ref") da3c54854197 ("btrfs: pass btrfs_ref to init_delayed_ref_common") f2e69a77aa51 ("btrfs: move ref_root into btrfs_ref") 4d09b4e942bc ("btrfs: do not use a function to initialize btrfs_ref") d3fbb00f5e21 ("btrfs: embed data_ref and tree_ref in btrfs_delayed_ref_node") 0eea355fc0f4 ("btrfs: add a helper to get the delayed ref node from the data/tree ref") 6de3595473b0 ("btrfs: compression: add error handling for missed page cache") 01b69bf9906b ("btrfs: convert put_file_data() to folios") 073bda7a5417 ("btrfs: zoned: add ASSERT and WARN for EXTENT_BUFFER_ZONED_ZEROOUT handling") 141fb8cd206a ("btrfs: qgroup: correctly model root qgroup rsv in convert") ef5a05c55704 ("btrfs: remove SLAB_MEM_SPREAD flag use") 06c9564980f1 ("btrfs: use KMEM_CACHE() to create btrfs_free_space cache") b2c7d55e4c4c ("btrfs: use KMEM_CACHE() to create delayed ref caches") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 42fac187b5c746227c92d024f1caf33bc1d337e4 Mon Sep 17 00:00:00 2001 From: Josef Bacik <josef(a)toxicpanda.com> Date: Thu, 11 Apr 2024 16:41:20 -0400 Subject: [PATCH] btrfs: check delayed refs when we're checking if a ref exists In the patch 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") I added some code to handle file systems that had been corrupted by a bug that incorrectly skipped updating the drop progress key while dropping a snapshot. This code would check to see if we had already deleted our reference for a child block, and skip the deletion if we had already. Unfortunately there is a bug, as the check would only check the on-disk references. I made an incorrect assumption that blocks in an already deleted snapshot that was having the deletion resume on mount wouldn't be modified. If we have 2 pending deleted snapshots that share blocks, we can easily modify the rules for a block. Take the following example subvolume a exists, and subvolume b is a snapshot of subvolume a. They share references to block 1. Block 1 will have 2 full references, one for subvolume a and one for subvolume b, and it belongs to subvolume a (btrfs_header_owner(block 1) == subvolume a). When deleting subvolume a, we will drop our full reference for block 1, and because we are the owner we will drop our full reference for all of block 1's children, convert block 1 to FULL BACKREF, and add a shared reference to all of block 1's children. Then we will start the snapshot deletion of subvolume b. We look up the extent info for block 1, which checks delayed refs and tells us that FULL BACKREF is set, so sets parent to the bytenr of block 1. However because this is a resumed snapshot deletion, we call into check_ref_exists(). Because check_ref_exists() only looks at the disk, it doesn't find the shared backref for the child of block 1, and thus returns 0 and we skip deleting the reference for the child of block 1 and continue. This orphans the child of block 1. The fix is to lookup the delayed refs, similar to what we do in btrfs_lookup_extent_info(). However we only care about whether the reference exists or not. If we fail to find our reference on disk, go look up the bytenr in the delayed refs, and if it exists look for an existing ref in the delayed ref head. If that exists then we know we can delete the reference safely and carry on. If it doesn't exist we know we have to skip over this block. This bug has existed since I introduced this fix, however requires having multiple deleted snapshots pending when we unmount. We noticed this in production because our shutdown path stops the container on the system, which deletes a bunch of subvolumes, and then reboots the box. This gives us plenty of opportunities to hit this issue. Looking at the history we've seen this occasionally in production, but we had a big spike recently thanks to faster machines getting jobs with multiple subvolumes in the job. Chris Mason wrote a reproducer which does the following mount /dev/nvme4n1 /btrfs btrfs subvol create /btrfs/s1 simoop -E -f 4k -n 200000 -z /btrfs/s1 while(true) ; do btrfs subvol snap /btrfs/s1 /btrfs/s2 simoop -f 4k -n 200000 -r 10 -z /btrfs/s2 btrfs subvol snap /btrfs/s2 /btrfs/s3 btrfs balance start -dusage=80 /btrfs btrfs subvol del /btrfs/s2 /btrfs/s3 umount /btrfs btrfsck /dev/nvme4n1 || exit 1 mount /dev/nvme4n1 /btrfs done On the second loop this would fail consistently, with my patch it has been running for hours and hasn't failed. I also used dm-log-writes to capture the state of the failure so I could debug the problem. Using the existing failure case to test my patch validated that it fixes the problem. Fixes: 78c52d9eb6b7 ("btrfs: check for refs on snapshot delete resume") CC: stable(a)vger.kernel.org # 5.4+ Reviewed-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 2ac9296edccb..06a9e0542d70 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -1134,6 +1134,73 @@ btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs, u64 byt return find_ref_head(delayed_refs, bytenr, false); } +static int find_comp(struct btrfs_delayed_ref_node *entry, u64 root, u64 parent) +{ + int type = parent ? BTRFS_SHARED_BLOCK_REF_KEY : BTRFS_TREE_BLOCK_REF_KEY; + + if (type < entry->type) + return -1; + if (type > entry->type) + return 1; + + if (type == BTRFS_TREE_BLOCK_REF_KEY) { + if (root < entry->ref_root) + return -1; + if (root > entry->ref_root) + return 1; + } else { + if (parent < entry->parent) + return -1; + if (parent > entry->parent) + return 1; + } + return 0; +} + +/* + * Check to see if a given root/parent reference is attached to the head. This + * only checks for BTRFS_ADD_DELAYED_REF references that match, as that + * indicates the reference exists for the given root or parent. This is for + * tree blocks only. + * + * @head: the head of the bytenr we're searching. + * @root: the root objectid of the reference if it is a normal reference. + * @parent: the parent if this is a shared backref. + */ +bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head, + u64 root, u64 parent) +{ + struct rb_node *node; + bool found = false; + + lockdep_assert_held(&head->mutex); + + spin_lock(&head->lock); + node = head->ref_tree.rb_root.rb_node; + while (node) { + struct btrfs_delayed_ref_node *entry; + int ret; + + entry = rb_entry(node, struct btrfs_delayed_ref_node, ref_node); + ret = find_comp(entry, root, parent); + if (ret < 0) { + node = node->rb_left; + } else if (ret > 0) { + node = node->rb_right; + } else { + /* + * We only want to count ADD actions, as drops mean the + * ref doesn't exist. + */ + if (entry->action == BTRFS_ADD_DELAYED_REF) + found = true; + break; + } + } + spin_unlock(&head->lock); + return found; +} + void __cold btrfs_delayed_ref_exit(void) { kmem_cache_destroy(btrfs_delayed_ref_head_cachep); diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index ef15e998be03..05f634eb472d 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -389,6 +389,8 @@ void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info); int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info, enum btrfs_reserve_flush_enum flush); bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info); +bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head, + u64 root, u64 parent); static inline u64 btrfs_delayed_ref_owner(struct btrfs_delayed_ref_node *node) { diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index ff9f0d41987e..feec49e6f9c8 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5472,23 +5472,62 @@ static int check_ref_exists(struct btrfs_trans_handle *trans, struct btrfs_root *root, u64 bytenr, u64 parent, int level) { + struct btrfs_delayed_ref_root *delayed_refs; + struct btrfs_delayed_ref_head *head; struct btrfs_path *path; struct btrfs_extent_inline_ref *iref; int ret; + bool exists = false; path = btrfs_alloc_path(); if (!path) return -ENOMEM; - +again: ret = lookup_extent_backref(trans, path, &iref, bytenr, root->fs_info->nodesize, parent, btrfs_root_id(root), level, 0); + if (ret != -ENOENT) { + /* + * If we get 0 then we found our reference, return 1, else + * return the error if it's not -ENOENT; + */ + btrfs_free_path(path); + return (ret < 0 ) ? ret : 1; + } + + /* + * We could have a delayed ref with this reference, so look it up while + * we're holding the path open to make sure we don't race with the + * delayed ref running. + */ + delayed_refs = &trans->transaction->delayed_refs; + spin_lock(&delayed_refs->lock); + head = btrfs_find_delayed_ref_head(delayed_refs, bytenr); + if (!head) + goto out; + if (!mutex_trylock(&head->mutex)) { + /* + * We're contended, means that the delayed ref is running, get a + * reference and wait for the ref head to be complete and then + * try again. + */ + refcount_inc(&head->refs); + spin_unlock(&delayed_refs->lock); + + btrfs_release_path(path); + + mutex_lock(&head->mutex); + mutex_unlock(&head->mutex); + btrfs_put_delayed_ref_head(head); + goto again; + } + + exists = btrfs_find_delayed_tree_ref(head, root->root_key.objectid, parent); + mutex_unlock(&head->mutex); +out: + spin_unlock(&delayed_refs->lock); btrfs_free_path(path); - if (ret == -ENOENT) - return 0; - if (ret < 0) - return ret; - return 1; + return exists ? 1 : 0; } /*

4 months, 3 weeks

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FAILED: patch "[PATCH] btrfs: send: allow cloning non-aligned extent if it ends at" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 46a6e10a1ab16cc71d4a3cab73e79aabadd6b8ea # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024081915-scrubber-excretion-0f83@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: 46a6e10a1ab1 ("btrfs: send: allow cloning non-aligned extent if it ends at i_size") 4e00422ee626 ("btrfs: replace sb::s_blocksize by fs_info::sectorsize") 3ea4dc5bf00c ("btrfs: send: send compressed extents with encoded writes") 6fe81a3a3ac8 ("btrfs: balance btree dirty pages and delayed items after clone and dedupe") 152555b39ceb ("btrfs: send: avoid trashing the page cache") 521b6803f22e ("btrfs: send: keep the current inode open while processing it") 1c6cbbbeeeca ("btrfs: remove inode_dio_wait() calls when starting reflink operations") 6b1f86f8e9c7 ("Merge tag 'folio-5.18b' of git://git.infradead.org/users/willy/pagecache") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 46a6e10a1ab16cc71d4a3cab73e79aabadd6b8ea Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Mon, 12 Aug 2024 14:18:06 +0100 Subject: [PATCH] btrfs: send: allow cloning non-aligned extent if it ends at i_size If we a find that an extent is shared but its end offset is not sector size aligned, then we don't clone it and issue write operations instead. This is because the reflink (remap_file_range) operation does not allow to clone unaligned ranges, except if the end offset of the range matches the i_size of the source and destination files (and the start offset is sector size aligned). While this is not incorrect because send can only guarantee that a file has the same data in the source and destination snapshots, it's not optimal and generates confusion and surprising behaviour for users. For example, running this test: $ cat test.sh #!/bin/bash DEV=/dev/sdi MNT=/mnt/sdi mkfs.btrfs -f $DEV mount $DEV $MNT # Use a file size not aligned to any possible sector size. file_size=$((1 * 1024 * 1024 + 5)) # 1MB + 5 bytes dd if=/dev/random of=$MNT/foo bs=$file_size count=1 cp --reflink=always $MNT/foo $MNT/bar btrfs subvolume snapshot -r $MNT/ $MNT/snap rm -f /tmp/send-test btrfs send -f /tmp/send-test $MNT/snap umount $MNT mkfs.btrfs -f $DEV mount $DEV $MNT btrfs receive -vv -f /tmp/send-test $MNT xfs_io -r -c "fiemap -v" $MNT/snap/bar umount $MNT Gives the following result: (...) mkfile o258-7-0 rename o258-7-0 -> bar write bar - offset=0 length=49152 write bar - offset=49152 length=49152 write bar - offset=98304 length=49152 write bar - offset=147456 length=49152 write bar - offset=196608 length=49152 write bar - offset=245760 length=49152 write bar - offset=294912 length=49152 write bar - offset=344064 length=49152 write bar - offset=393216 length=49152 write bar - offset=442368 length=49152 write bar - offset=491520 length=49152 write bar - offset=540672 length=49152 write bar - offset=589824 length=49152 write bar - offset=638976 length=49152 write bar - offset=688128 length=49152 write bar - offset=737280 length=49152 write bar - offset=786432 length=49152 write bar - offset=835584 length=49152 write bar - offset=884736 length=49152 write bar - offset=933888 length=49152 write bar - offset=983040 length=49152 write bar - offset=1032192 length=16389 chown bar - uid=0, gid=0 chmod bar - mode=0644 utimes bar utimes BTRFS_IOC_SET_RECEIVED_SUBVOL uuid=06d640da-9ca1-604c-b87c-3375175a8eb3, stransid=7 /mnt/sdi/snap/bar: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..2055]: 26624..28679 2056 0x1 There's no clone operation to clone extents from the file foo into file bar and fiemap confirms there's no shared flag (0x2000). So update send_write_or_clone() so that it proceeds with cloning if the source and destination ranges end at the i_size of the respective files. After this changes the result of the test is: (...) mkfile o258-7-0 rename o258-7-0 -> bar clone bar - source=foo source offset=0 offset=0 length=1048581 chown bar - uid=0, gid=0 chmod bar - mode=0644 utimes bar utimes BTRFS_IOC_SET_RECEIVED_SUBVOL uuid=582420f3-ea7d-564e-bbe5-ce440d622190, stransid=7 /mnt/sdi/snap/bar: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..2055]: 26624..28679 2056 0x2001 A test case for fstests will also follow up soon. Link: https://github.com/kdave/btrfs-progs/issues/572#issuecomment-2282841416 CC: stable(a)vger.kernel.org # 5.10+ Reviewed-by: Qu Wenruo <wqu(a)suse.com> Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Reviewed-by: David Sterba <dsterba(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 4ca711a773ef..7fc692fc76e1 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -6157,25 +6157,51 @@ static int send_write_or_clone(struct send_ctx *sctx, u64 offset = key->offset; u64 end; u64 bs = sctx->send_root->fs_info->sectorsize; + struct btrfs_file_extent_item *ei; + u64 disk_byte; + u64 data_offset; + u64 num_bytes; + struct btrfs_inode_info info = { 0 }; end = min_t(u64, btrfs_file_extent_end(path), sctx->cur_inode_size); if (offset >= end) return 0; - if (clone_root && IS_ALIGNED(end, bs)) { - struct btrfs_file_extent_item *ei; - u64 disk_byte; - u64 data_offset; + num_bytes = end - offset; - ei = btrfs_item_ptr(path->nodes[0], path->slots[0], - struct btrfs_file_extent_item); - disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei); - data_offset = btrfs_file_extent_offset(path->nodes[0], ei); - ret = clone_range(sctx, path, clone_root, disk_byte, - data_offset, offset, end - offset); - } else { - ret = send_extent_data(sctx, path, offset, end - offset); - } + if (!clone_root) + goto write_data; + + if (IS_ALIGNED(end, bs)) + goto clone_data; + + /* + * If the extent end is not aligned, we can clone if the extent ends at + * the i_size of the inode and the clone range ends at the i_size of the + * source inode, otherwise the clone operation fails with -EINVAL. + */ + if (end != sctx->cur_inode_size) + goto write_data; + + ret = get_inode_info(clone_root->root, clone_root->ino, &info); + if (ret < 0) + return ret; + + if (clone_root->offset + num_bytes == info.size) + goto clone_data; + +write_data: + ret = send_extent_data(sctx, path, offset, num_bytes); + sctx->cur_inode_next_write_offset = end; + return ret; + +clone_data: + ei = btrfs_item_ptr(path->nodes[0], path->slots[0], + struct btrfs_file_extent_item); + disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei); + data_offset = btrfs_file_extent_offset(path->nodes[0], ei); + ret = clone_range(sctx, path, clone_root, disk_byte, data_offset, offset, + num_bytes); sctx->cur_inode_next_write_offset = end; return ret; }

4 months, 3 weeks

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FAILED: patch "[PATCH] btrfs: send: allow cloning non-aligned extent if it ends at" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 46a6e10a1ab16cc71d4a3cab73e79aabadd6b8ea # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024081913-cupped-curing-f315@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: 46a6e10a1ab1 ("btrfs: send: allow cloning non-aligned extent if it ends at i_size") 4e00422ee626 ("btrfs: replace sb::s_blocksize by fs_info::sectorsize") 3ea4dc5bf00c ("btrfs: send: send compressed extents with encoded writes") 6fe81a3a3ac8 ("btrfs: balance btree dirty pages and delayed items after clone and dedupe") 152555b39ceb ("btrfs: send: avoid trashing the page cache") 521b6803f22e ("btrfs: send: keep the current inode open while processing it") 1c6cbbbeeeca ("btrfs: remove inode_dio_wait() calls when starting reflink operations") 6b1f86f8e9c7 ("Merge tag 'folio-5.18b' of git://git.infradead.org/users/willy/pagecache") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 46a6e10a1ab16cc71d4a3cab73e79aabadd6b8ea Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Mon, 12 Aug 2024 14:18:06 +0100 Subject: [PATCH] btrfs: send: allow cloning non-aligned extent if it ends at i_size If we a find that an extent is shared but its end offset is not sector size aligned, then we don't clone it and issue write operations instead. This is because the reflink (remap_file_range) operation does not allow to clone unaligned ranges, except if the end offset of the range matches the i_size of the source and destination files (and the start offset is sector size aligned). While this is not incorrect because send can only guarantee that a file has the same data in the source and destination snapshots, it's not optimal and generates confusion and surprising behaviour for users. For example, running this test: $ cat test.sh #!/bin/bash DEV=/dev/sdi MNT=/mnt/sdi mkfs.btrfs -f $DEV mount $DEV $MNT # Use a file size not aligned to any possible sector size. file_size=$((1 * 1024 * 1024 + 5)) # 1MB + 5 bytes dd if=/dev/random of=$MNT/foo bs=$file_size count=1 cp --reflink=always $MNT/foo $MNT/bar btrfs subvolume snapshot -r $MNT/ $MNT/snap rm -f /tmp/send-test btrfs send -f /tmp/send-test $MNT/snap umount $MNT mkfs.btrfs -f $DEV mount $DEV $MNT btrfs receive -vv -f /tmp/send-test $MNT xfs_io -r -c "fiemap -v" $MNT/snap/bar umount $MNT Gives the following result: (...) mkfile o258-7-0 rename o258-7-0 -> bar write bar - offset=0 length=49152 write bar - offset=49152 length=49152 write bar - offset=98304 length=49152 write bar - offset=147456 length=49152 write bar - offset=196608 length=49152 write bar - offset=245760 length=49152 write bar - offset=294912 length=49152 write bar - offset=344064 length=49152 write bar - offset=393216 length=49152 write bar - offset=442368 length=49152 write bar - offset=491520 length=49152 write bar - offset=540672 length=49152 write bar - offset=589824 length=49152 write bar - offset=638976 length=49152 write bar - offset=688128 length=49152 write bar - offset=737280 length=49152 write bar - offset=786432 length=49152 write bar - offset=835584 length=49152 write bar - offset=884736 length=49152 write bar - offset=933888 length=49152 write bar - offset=983040 length=49152 write bar - offset=1032192 length=16389 chown bar - uid=0, gid=0 chmod bar - mode=0644 utimes bar utimes BTRFS_IOC_SET_RECEIVED_SUBVOL uuid=06d640da-9ca1-604c-b87c-3375175a8eb3, stransid=7 /mnt/sdi/snap/bar: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..2055]: 26624..28679 2056 0x1 There's no clone operation to clone extents from the file foo into file bar and fiemap confirms there's no shared flag (0x2000). So update send_write_or_clone() so that it proceeds with cloning if the source and destination ranges end at the i_size of the respective files. After this changes the result of the test is: (...) mkfile o258-7-0 rename o258-7-0 -> bar clone bar - source=foo source offset=0 offset=0 length=1048581 chown bar - uid=0, gid=0 chmod bar - mode=0644 utimes bar utimes BTRFS_IOC_SET_RECEIVED_SUBVOL uuid=582420f3-ea7d-564e-bbe5-ce440d622190, stransid=7 /mnt/sdi/snap/bar: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..2055]: 26624..28679 2056 0x2001 A test case for fstests will also follow up soon. Link: https://github.com/kdave/btrfs-progs/issues/572#issuecomment-2282841416 CC: stable(a)vger.kernel.org # 5.10+ Reviewed-by: Qu Wenruo <wqu(a)suse.com> Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Reviewed-by: David Sterba <dsterba(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 4ca711a773ef..7fc692fc76e1 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -6157,25 +6157,51 @@ static int send_write_or_clone(struct send_ctx *sctx, u64 offset = key->offset; u64 end; u64 bs = sctx->send_root->fs_info->sectorsize; + struct btrfs_file_extent_item *ei; + u64 disk_byte; + u64 data_offset; + u64 num_bytes; + struct btrfs_inode_info info = { 0 }; end = min_t(u64, btrfs_file_extent_end(path), sctx->cur_inode_size); if (offset >= end) return 0; - if (clone_root && IS_ALIGNED(end, bs)) { - struct btrfs_file_extent_item *ei; - u64 disk_byte; - u64 data_offset; + num_bytes = end - offset; - ei = btrfs_item_ptr(path->nodes[0], path->slots[0], - struct btrfs_file_extent_item); - disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei); - data_offset = btrfs_file_extent_offset(path->nodes[0], ei); - ret = clone_range(sctx, path, clone_root, disk_byte, - data_offset, offset, end - offset); - } else { - ret = send_extent_data(sctx, path, offset, end - offset); - } + if (!clone_root) + goto write_data; + + if (IS_ALIGNED(end, bs)) + goto clone_data; + + /* + * If the extent end is not aligned, we can clone if the extent ends at + * the i_size of the inode and the clone range ends at the i_size of the + * source inode, otherwise the clone operation fails with -EINVAL. + */ + if (end != sctx->cur_inode_size) + goto write_data; + + ret = get_inode_info(clone_root->root, clone_root->ino, &info); + if (ret < 0) + return ret; + + if (clone_root->offset + num_bytes == info.size) + goto clone_data; + +write_data: + ret = send_extent_data(sctx, path, offset, num_bytes); + sctx->cur_inode_next_write_offset = end; + return ret; + +clone_data: + ei = btrfs_item_ptr(path->nodes[0], path->slots[0], + struct btrfs_file_extent_item); + disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei); + data_offset = btrfs_file_extent_offset(path->nodes[0], ei); + ret = clone_range(sctx, path, clone_root, disk_byte, data_offset, offset, + num_bytes); sctx->cur_inode_next_write_offset = end; return ret; }

4 months, 3 weeks

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FAILED: patch "[PATCH] btrfs: send: allow cloning non-aligned extent if it ends at" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 46a6e10a1ab16cc71d4a3cab73e79aabadd6b8ea # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024081911-shrivel-overstay-1394@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: 46a6e10a1ab1 ("btrfs: send: allow cloning non-aligned extent if it ends at i_size") 4e00422ee626 ("btrfs: replace sb::s_blocksize by fs_info::sectorsize") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 46a6e10a1ab16cc71d4a3cab73e79aabadd6b8ea Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Mon, 12 Aug 2024 14:18:06 +0100 Subject: [PATCH] btrfs: send: allow cloning non-aligned extent if it ends at i_size If we a find that an extent is shared but its end offset is not sector size aligned, then we don't clone it and issue write operations instead. This is because the reflink (remap_file_range) operation does not allow to clone unaligned ranges, except if the end offset of the range matches the i_size of the source and destination files (and the start offset is sector size aligned). While this is not incorrect because send can only guarantee that a file has the same data in the source and destination snapshots, it's not optimal and generates confusion and surprising behaviour for users. For example, running this test: $ cat test.sh #!/bin/bash DEV=/dev/sdi MNT=/mnt/sdi mkfs.btrfs -f $DEV mount $DEV $MNT # Use a file size not aligned to any possible sector size. file_size=$((1 * 1024 * 1024 + 5)) # 1MB + 5 bytes dd if=/dev/random of=$MNT/foo bs=$file_size count=1 cp --reflink=always $MNT/foo $MNT/bar btrfs subvolume snapshot -r $MNT/ $MNT/snap rm -f /tmp/send-test btrfs send -f /tmp/send-test $MNT/snap umount $MNT mkfs.btrfs -f $DEV mount $DEV $MNT btrfs receive -vv -f /tmp/send-test $MNT xfs_io -r -c "fiemap -v" $MNT/snap/bar umount $MNT Gives the following result: (...) mkfile o258-7-0 rename o258-7-0 -> bar write bar - offset=0 length=49152 write bar - offset=49152 length=49152 write bar - offset=98304 length=49152 write bar - offset=147456 length=49152 write bar - offset=196608 length=49152 write bar - offset=245760 length=49152 write bar - offset=294912 length=49152 write bar - offset=344064 length=49152 write bar - offset=393216 length=49152 write bar - offset=442368 length=49152 write bar - offset=491520 length=49152 write bar - offset=540672 length=49152 write bar - offset=589824 length=49152 write bar - offset=638976 length=49152 write bar - offset=688128 length=49152 write bar - offset=737280 length=49152 write bar - offset=786432 length=49152 write bar - offset=835584 length=49152 write bar - offset=884736 length=49152 write bar - offset=933888 length=49152 write bar - offset=983040 length=49152 write bar - offset=1032192 length=16389 chown bar - uid=0, gid=0 chmod bar - mode=0644 utimes bar utimes BTRFS_IOC_SET_RECEIVED_SUBVOL uuid=06d640da-9ca1-604c-b87c-3375175a8eb3, stransid=7 /mnt/sdi/snap/bar: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..2055]: 26624..28679 2056 0x1 There's no clone operation to clone extents from the file foo into file bar and fiemap confirms there's no shared flag (0x2000). So update send_write_or_clone() so that it proceeds with cloning if the source and destination ranges end at the i_size of the respective files. After this changes the result of the test is: (...) mkfile o258-7-0 rename o258-7-0 -> bar clone bar - source=foo source offset=0 offset=0 length=1048581 chown bar - uid=0, gid=0 chmod bar - mode=0644 utimes bar utimes BTRFS_IOC_SET_RECEIVED_SUBVOL uuid=582420f3-ea7d-564e-bbe5-ce440d622190, stransid=7 /mnt/sdi/snap/bar: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..2055]: 26624..28679 2056 0x2001 A test case for fstests will also follow up soon. Link: https://github.com/kdave/btrfs-progs/issues/572#issuecomment-2282841416 CC: stable(a)vger.kernel.org # 5.10+ Reviewed-by: Qu Wenruo <wqu(a)suse.com> Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Reviewed-by: David Sterba <dsterba(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 4ca711a773ef..7fc692fc76e1 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -6157,25 +6157,51 @@ static int send_write_or_clone(struct send_ctx *sctx, u64 offset = key->offset; u64 end; u64 bs = sctx->send_root->fs_info->sectorsize; + struct btrfs_file_extent_item *ei; + u64 disk_byte; + u64 data_offset; + u64 num_bytes; + struct btrfs_inode_info info = { 0 }; end = min_t(u64, btrfs_file_extent_end(path), sctx->cur_inode_size); if (offset >= end) return 0; - if (clone_root && IS_ALIGNED(end, bs)) { - struct btrfs_file_extent_item *ei; - u64 disk_byte; - u64 data_offset; + num_bytes = end - offset; - ei = btrfs_item_ptr(path->nodes[0], path->slots[0], - struct btrfs_file_extent_item); - disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei); - data_offset = btrfs_file_extent_offset(path->nodes[0], ei); - ret = clone_range(sctx, path, clone_root, disk_byte, - data_offset, offset, end - offset); - } else { - ret = send_extent_data(sctx, path, offset, end - offset); - } + if (!clone_root) + goto write_data; + + if (IS_ALIGNED(end, bs)) + goto clone_data; + + /* + * If the extent end is not aligned, we can clone if the extent ends at + * the i_size of the inode and the clone range ends at the i_size of the + * source inode, otherwise the clone operation fails with -EINVAL. + */ + if (end != sctx->cur_inode_size) + goto write_data; + + ret = get_inode_info(clone_root->root, clone_root->ino, &info); + if (ret < 0) + return ret; + + if (clone_root->offset + num_bytes == info.size) + goto clone_data; + +write_data: + ret = send_extent_data(sctx, path, offset, num_bytes); + sctx->cur_inode_next_write_offset = end; + return ret; + +clone_data: + ei = btrfs_item_ptr(path->nodes[0], path->slots[0], + struct btrfs_file_extent_item); + disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei); + data_offset = btrfs_file_extent_offset(path->nodes[0], ei); + ret = clone_range(sctx, path, clone_root, disk_byte, data_offset, offset, + num_bytes); sctx->cur_inode_next_write_offset = end; return ret; }

4 months, 3 weeks

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FAILED: patch "[PATCH] btrfs: send: allow cloning non-aligned extent if it ends at" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 46a6e10a1ab16cc71d4a3cab73e79aabadd6b8ea # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024081909-blunt-glass-4ea5@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: 46a6e10a1ab1 ("btrfs: send: allow cloning non-aligned extent if it ends at i_size") 4e00422ee626 ("btrfs: replace sb::s_blocksize by fs_info::sectorsize") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 46a6e10a1ab16cc71d4a3cab73e79aabadd6b8ea Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Mon, 12 Aug 2024 14:18:06 +0100 Subject: [PATCH] btrfs: send: allow cloning non-aligned extent if it ends at i_size If we a find that an extent is shared but its end offset is not sector size aligned, then we don't clone it and issue write operations instead. This is because the reflink (remap_file_range) operation does not allow to clone unaligned ranges, except if the end offset of the range matches the i_size of the source and destination files (and the start offset is sector size aligned). While this is not incorrect because send can only guarantee that a file has the same data in the source and destination snapshots, it's not optimal and generates confusion and surprising behaviour for users. For example, running this test: $ cat test.sh #!/bin/bash DEV=/dev/sdi MNT=/mnt/sdi mkfs.btrfs -f $DEV mount $DEV $MNT # Use a file size not aligned to any possible sector size. file_size=$((1 * 1024 * 1024 + 5)) # 1MB + 5 bytes dd if=/dev/random of=$MNT/foo bs=$file_size count=1 cp --reflink=always $MNT/foo $MNT/bar btrfs subvolume snapshot -r $MNT/ $MNT/snap rm -f /tmp/send-test btrfs send -f /tmp/send-test $MNT/snap umount $MNT mkfs.btrfs -f $DEV mount $DEV $MNT btrfs receive -vv -f /tmp/send-test $MNT xfs_io -r -c "fiemap -v" $MNT/snap/bar umount $MNT Gives the following result: (...) mkfile o258-7-0 rename o258-7-0 -> bar write bar - offset=0 length=49152 write bar - offset=49152 length=49152 write bar - offset=98304 length=49152 write bar - offset=147456 length=49152 write bar - offset=196608 length=49152 write bar - offset=245760 length=49152 write bar - offset=294912 length=49152 write bar - offset=344064 length=49152 write bar - offset=393216 length=49152 write bar - offset=442368 length=49152 write bar - offset=491520 length=49152 write bar - offset=540672 length=49152 write bar - offset=589824 length=49152 write bar - offset=638976 length=49152 write bar - offset=688128 length=49152 write bar - offset=737280 length=49152 write bar - offset=786432 length=49152 write bar - offset=835584 length=49152 write bar - offset=884736 length=49152 write bar - offset=933888 length=49152 write bar - offset=983040 length=49152 write bar - offset=1032192 length=16389 chown bar - uid=0, gid=0 chmod bar - mode=0644 utimes bar utimes BTRFS_IOC_SET_RECEIVED_SUBVOL uuid=06d640da-9ca1-604c-b87c-3375175a8eb3, stransid=7 /mnt/sdi/snap/bar: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..2055]: 26624..28679 2056 0x1 There's no clone operation to clone extents from the file foo into file bar and fiemap confirms there's no shared flag (0x2000). So update send_write_or_clone() so that it proceeds with cloning if the source and destination ranges end at the i_size of the respective files. After this changes the result of the test is: (...) mkfile o258-7-0 rename o258-7-0 -> bar clone bar - source=foo source offset=0 offset=0 length=1048581 chown bar - uid=0, gid=0 chmod bar - mode=0644 utimes bar utimes BTRFS_IOC_SET_RECEIVED_SUBVOL uuid=582420f3-ea7d-564e-bbe5-ce440d622190, stransid=7 /mnt/sdi/snap/bar: EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS 0: [0..2055]: 26624..28679 2056 0x2001 A test case for fstests will also follow up soon. Link: https://github.com/kdave/btrfs-progs/issues/572#issuecomment-2282841416 CC: stable(a)vger.kernel.org # 5.10+ Reviewed-by: Qu Wenruo <wqu(a)suse.com> Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Reviewed-by: David Sterba <dsterba(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 4ca711a773ef..7fc692fc76e1 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -6157,25 +6157,51 @@ static int send_write_or_clone(struct send_ctx *sctx, u64 offset = key->offset; u64 end; u64 bs = sctx->send_root->fs_info->sectorsize; + struct btrfs_file_extent_item *ei; + u64 disk_byte; + u64 data_offset; + u64 num_bytes; + struct btrfs_inode_info info = { 0 }; end = min_t(u64, btrfs_file_extent_end(path), sctx->cur_inode_size); if (offset >= end) return 0; - if (clone_root && IS_ALIGNED(end, bs)) { - struct btrfs_file_extent_item *ei; - u64 disk_byte; - u64 data_offset; + num_bytes = end - offset; - ei = btrfs_item_ptr(path->nodes[0], path->slots[0], - struct btrfs_file_extent_item); - disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei); - data_offset = btrfs_file_extent_offset(path->nodes[0], ei); - ret = clone_range(sctx, path, clone_root, disk_byte, - data_offset, offset, end - offset); - } else { - ret = send_extent_data(sctx, path, offset, end - offset); - } + if (!clone_root) + goto write_data; + + if (IS_ALIGNED(end, bs)) + goto clone_data; + + /* + * If the extent end is not aligned, we can clone if the extent ends at + * the i_size of the inode and the clone range ends at the i_size of the + * source inode, otherwise the clone operation fails with -EINVAL. + */ + if (end != sctx->cur_inode_size) + goto write_data; + + ret = get_inode_info(clone_root->root, clone_root->ino, &info); + if (ret < 0) + return ret; + + if (clone_root->offset + num_bytes == info.size) + goto clone_data; + +write_data: + ret = send_extent_data(sctx, path, offset, num_bytes); + sctx->cur_inode_next_write_offset = end; + return ret; + +clone_data: + ei = btrfs_item_ptr(path->nodes[0], path->slots[0], + struct btrfs_file_extent_item); + disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei); + data_offset = btrfs_file_extent_offset(path->nodes[0], ei); + ret = clone_range(sctx, path, clone_root, disk_byte, data_offset, offset, + num_bytes); sctx->cur_inode_next_write_offset = end; return ret; }

4 months, 3 weeks

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FAILED: patch "[PATCH] btrfs: tree-checker: reject BTRFS_FT_UNKNOWN dir type" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 31723c9542dba1681cc3720571fdf12ffe0eddd9 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024081954-purplish-scarecrow-7568@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: 31723c9542db ("btrfs: tree-checker: reject BTRFS_FT_UNKNOWN dir type") 94a48aef49f2 ("btrfs: extend btrfs_dir_item type to store encryption status") e43eec81c516 ("btrfs: use struct qstr instead of name and namelen pairs") 07e81dc94474 ("btrfs: move accessor helpers into accessors.h") ad1ac5012c2b ("btrfs: move btrfs_map_token to accessors") 55e5cfd36da5 ("btrfs: remove fs_info::pending_changes and related code") 7966a6b5959b ("btrfs: move fs_info::flags enum to fs.h") fc97a410bd78 ("btrfs: move mount option definitions to fs.h") 0d3a9cf8c306 ("btrfs: convert incompat and compat flag test helpers to macros") ec8eb376e271 ("btrfs: move BTRFS_FS_STATE* definitions and helpers to fs.h") 9b569ea0be6f ("btrfs: move the printk helpers out of ctree.h") e118578a8df7 ("btrfs: move assert helpers out of ctree.h") c7f13d428ea1 ("btrfs: move fs wide helpers out of ctree.h") 63a7cb130718 ("btrfs: auto enable discard=async when possible") 7a66eda351ba ("btrfs: move the btrfs_verity_descriptor_item defs up in ctree.h") 956504a331a6 ("btrfs: move trans_handle_cachep out of ctree.h") f1e5c6185ca1 ("btrfs: move flush related definitions to space-info.h") ed4c491a3db2 ("btrfs: move BTRFS_MAX_MIRRORS into scrub.c") 4300c58f8090 ("btrfs: move btrfs on-disk definitions out of ctree.h") d60d956eb41f ("btrfs: remove unused set/clear_pending_info helpers") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 31723c9542dba1681cc3720571fdf12ffe0eddd9 Mon Sep 17 00:00:00 2001 From: Qu Wenruo <wqu(a)suse.com> Date: Mon, 12 Aug 2024 08:52:44 +0930 Subject: [PATCH] btrfs: tree-checker: reject BTRFS_FT_UNKNOWN dir type [REPORT] There is a bug report that kernel is rejecting a mismatching inode mode and its dir item: [ 1881.553937] BTRFS critical (device dm-0): inode mode mismatch with dir: inode mode=040700 btrfs type=2 dir type=0 [CAUSE] It looks like the inode mode is correct, while the dir item type 0 is BTRFS_FT_UNKNOWN, which should not be generated by btrfs at all. This may be caused by a memory bit flip. [ENHANCEMENT] Although tree-checker is not able to do any cross-leaf verification, for this particular case we can at least reject any dir type with BTRFS_FT_UNKNOWN. So here we enhance the dir type check from [0, BTRFS_FT_MAX), to (0, BTRFS_FT_MAX). Although the existing corruption can not be fixed just by such enhanced checking, it should prevent the same 0x2->0x0 bitflip for dir type to reach disk in the future. Reported-by: Kota <nospam(a)kota.moe> Link: https://lore.kernel.org/linux-btrfs/CACsxjPYnQF9ZF-0OhH16dAx50=BXXOcP74MxBc… CC: stable(a)vger.kernel.org # 5.4+ Signed-off-by: Qu Wenruo <wqu(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index a825fa598e3c..6f1e2f2215d9 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -569,9 +569,10 @@ static int check_dir_item(struct extent_buffer *leaf, /* dir type check */ dir_type = btrfs_dir_ftype(leaf, di); - if (unlikely(dir_type >= BTRFS_FT_MAX)) { + if (unlikely(dir_type <= BTRFS_FT_UNKNOWN || + dir_type >= BTRFS_FT_MAX)) { dir_item_err(leaf, slot, - "invalid dir item type, have %u expect [0, %u)", + "invalid dir item type, have %u expect (0, %u)", dir_type, BTRFS_FT_MAX); return -EUCLEAN; }

4 months, 3 weeks

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