March 2021 - Linux-stable-mirror

FAILED: patch "[PATCH] btrfs: fix race between extent freeing/allocation when using" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 3c17916510428dbccdf657de050c34e208347089 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov <nborisov(a)suse.com> Date: Mon, 8 Feb 2021 10:26:54 +0200 Subject: [PATCH] btrfs: fix race between extent freeing/allocation when using bitmaps During allocation the allocator will try to allocate an extent using cluster policy. Once the current cluster is exhausted it will remove the entry under btrfs_free_cluster::lock and subsequently acquire btrfs_free_space_ctl::tree_lock to dispose of the already-deleted entry and adjust btrfs_free_space_ctl::total_bitmap. This poses a problem because there exists a race condition between removing the entry under one lock and doing the necessary accounting holding a different lock since extent freeing only uses the 2nd lock. This can result in the following situation: T1: T2: btrfs_alloc_from_cluster insert_into_bitmap <holds tree_lock> if (entry->bytes == 0) if (block_group && !list_empty(&block_group->cluster_list)) { rb_erase(entry) spin_unlock(&cluster->lock); (total_bitmaps is still 4) spin_lock(&cluster->lock); <doesn't find entry in cluster->root> spin_lock(&ctl->tree_lock); <goes to new_bitmap label, adds <blocked since T2 holds tree_lock> <a new entry and calls add_new_bitmap> recalculate_thresholds <crashes, due to total_bitmaps becoming 5 and triggering an ASSERT> To fix this ensure that once depleted, the cluster entry is deleted when both cluster lock and tree locks are held in the allocator (T1), this ensures that even if there is a race with a concurrent insert_into_bitmap call it will correctly find the entry in the cluster and add the new space to it. CC: <stable(a)vger.kernel.org> # 4.4+ Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Nikolay Borisov <nborisov(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 5400294bd271..abcf951e6b44 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -3125,8 +3125,6 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, entry->bytes -= bytes; } - if (entry->bytes == 0) - rb_erase(&entry->offset_index, &cluster->root); break; } out: @@ -3143,7 +3141,10 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, ctl->free_space -= bytes; if (!entry->bitmap && !btrfs_free_space_trimmed(entry)) ctl->discardable_bytes[BTRFS_STAT_CURR] -= bytes; + + spin_lock(&cluster->lock); if (entry->bytes == 0) { + rb_erase(&entry->offset_index, &cluster->root); ctl->free_extents--; if (entry->bitmap) { kmem_cache_free(btrfs_free_space_bitmap_cachep, @@ -3156,6 +3157,7 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, kmem_cache_free(btrfs_free_space_cachep, entry); } + spin_unlock(&cluster->lock); spin_unlock(&ctl->tree_lock); return ret;

3 years, 7 months

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FAILED: patch "[PATCH] btrfs: fix race between extent freeing/allocation when using" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 3c17916510428dbccdf657de050c34e208347089 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov <nborisov(a)suse.com> Date: Mon, 8 Feb 2021 10:26:54 +0200 Subject: [PATCH] btrfs: fix race between extent freeing/allocation when using bitmaps During allocation the allocator will try to allocate an extent using cluster policy. Once the current cluster is exhausted it will remove the entry under btrfs_free_cluster::lock and subsequently acquire btrfs_free_space_ctl::tree_lock to dispose of the already-deleted entry and adjust btrfs_free_space_ctl::total_bitmap. This poses a problem because there exists a race condition between removing the entry under one lock and doing the necessary accounting holding a different lock since extent freeing only uses the 2nd lock. This can result in the following situation: T1: T2: btrfs_alloc_from_cluster insert_into_bitmap <holds tree_lock> if (entry->bytes == 0) if (block_group && !list_empty(&block_group->cluster_list)) { rb_erase(entry) spin_unlock(&cluster->lock); (total_bitmaps is still 4) spin_lock(&cluster->lock); <doesn't find entry in cluster->root> spin_lock(&ctl->tree_lock); <goes to new_bitmap label, adds <blocked since T2 holds tree_lock> <a new entry and calls add_new_bitmap> recalculate_thresholds <crashes, due to total_bitmaps becoming 5 and triggering an ASSERT> To fix this ensure that once depleted, the cluster entry is deleted when both cluster lock and tree locks are held in the allocator (T1), this ensures that even if there is a race with a concurrent insert_into_bitmap call it will correctly find the entry in the cluster and add the new space to it. CC: <stable(a)vger.kernel.org> # 4.4+ Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Nikolay Borisov <nborisov(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 5400294bd271..abcf951e6b44 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -3125,8 +3125,6 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, entry->bytes -= bytes; } - if (entry->bytes == 0) - rb_erase(&entry->offset_index, &cluster->root); break; } out: @@ -3143,7 +3141,10 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, ctl->free_space -= bytes; if (!entry->bitmap && !btrfs_free_space_trimmed(entry)) ctl->discardable_bytes[BTRFS_STAT_CURR] -= bytes; + + spin_lock(&cluster->lock); if (entry->bytes == 0) { + rb_erase(&entry->offset_index, &cluster->root); ctl->free_extents--; if (entry->bitmap) { kmem_cache_free(btrfs_free_space_bitmap_cachep, @@ -3156,6 +3157,7 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, kmem_cache_free(btrfs_free_space_cachep, entry); } + spin_unlock(&cluster->lock); spin_unlock(&ctl->tree_lock); return ret;

3 years, 7 months

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FAILED: patch "[PATCH] btrfs: fix race between extent freeing/allocation when using" failed to apply to 4.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.4-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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 3c17916510428dbccdf657de050c34e208347089 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov <nborisov(a)suse.com> Date: Mon, 8 Feb 2021 10:26:54 +0200 Subject: [PATCH] btrfs: fix race between extent freeing/allocation when using bitmaps During allocation the allocator will try to allocate an extent using cluster policy. Once the current cluster is exhausted it will remove the entry under btrfs_free_cluster::lock and subsequently acquire btrfs_free_space_ctl::tree_lock to dispose of the already-deleted entry and adjust btrfs_free_space_ctl::total_bitmap. This poses a problem because there exists a race condition between removing the entry under one lock and doing the necessary accounting holding a different lock since extent freeing only uses the 2nd lock. This can result in the following situation: T1: T2: btrfs_alloc_from_cluster insert_into_bitmap <holds tree_lock> if (entry->bytes == 0) if (block_group && !list_empty(&block_group->cluster_list)) { rb_erase(entry) spin_unlock(&cluster->lock); (total_bitmaps is still 4) spin_lock(&cluster->lock); <doesn't find entry in cluster->root> spin_lock(&ctl->tree_lock); <goes to new_bitmap label, adds <blocked since T2 holds tree_lock> <a new entry and calls add_new_bitmap> recalculate_thresholds <crashes, due to total_bitmaps becoming 5 and triggering an ASSERT> To fix this ensure that once depleted, the cluster entry is deleted when both cluster lock and tree locks are held in the allocator (T1), this ensures that even if there is a race with a concurrent insert_into_bitmap call it will correctly find the entry in the cluster and add the new space to it. CC: <stable(a)vger.kernel.org> # 4.4+ Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Nikolay Borisov <nborisov(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 5400294bd271..abcf951e6b44 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -3125,8 +3125,6 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, entry->bytes -= bytes; } - if (entry->bytes == 0) - rb_erase(&entry->offset_index, &cluster->root); break; } out: @@ -3143,7 +3141,10 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, ctl->free_space -= bytes; if (!entry->bitmap && !btrfs_free_space_trimmed(entry)) ctl->discardable_bytes[BTRFS_STAT_CURR] -= bytes; + + spin_lock(&cluster->lock); if (entry->bytes == 0) { + rb_erase(&entry->offset_index, &cluster->root); ctl->free_extents--; if (entry->bitmap) { kmem_cache_free(btrfs_free_space_bitmap_cachep, @@ -3156,6 +3157,7 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group *block_group, kmem_cache_free(btrfs_free_space_cachep, entry); } + spin_unlock(&cluster->lock); spin_unlock(&ctl->tree_lock); return ret;

3 years, 7 months

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FAILED: patch "[PATCH] btrfs: tree-checker: do not error out if extent ref hash" 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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 1119a72e223f3073a604f8fccb3a470ccd8a4416 Mon Sep 17 00:00:00 2001 From: Josef Bacik <josef(a)toxicpanda.com> Date: Tue, 16 Feb 2021 15:43:22 -0500 Subject: [PATCH] btrfs: tree-checker: do not error out if extent ref hash doesn't match MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The tree checker checks the extent ref hash at read and write time to make sure we do not corrupt the file system. Generally extent references go inline, but if we have enough of them we need to make an item, which looks like key.objectid = <bytenr> key.type = <BTRFS_EXTENT_DATA_REF_KEY|BTRFS_TREE_BLOCK_REF_KEY> key.offset = hash(tree, owner, offset) However if key.offset collide with an unrelated extent reference we'll simply key.offset++ until we get something that doesn't collide. Obviously this doesn't match at tree checker time, and thus we error while writing out the transaction. This is relatively easy to reproduce, simply do something like the following xfs_io -f -c "pwrite 0 1M" file offset=2 for i in {0..10000} do xfs_io -c "reflink file 0 ${offset}M 1M" file offset=$(( offset + 2 )) done xfs_io -c "reflink file 0 17999258914816 1M" file xfs_io -c "reflink file 0 35998517829632 1M" file xfs_io -c "reflink file 0 53752752058368 1M" file btrfs filesystem sync And the sync will error out because we'll abort the transaction. The magic values above are used because they generate hash collisions with the first file in the main subvol. The fix for this is to remove the hash value check from tree checker, as we have no idea which offset ours should belong to. Reported-by: Tuomas Lähdekorpi <tuomas.lahdekorpi(a)gmail.com> Fixes: 0785a9aacf9d ("btrfs: tree-checker: Add EXTENT_DATA_REF check") 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> Reviewed-by: David Sterba <dsterba(a)suse.com> [ add comment] Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index 582061c7b547..f4ade821307d 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -1453,22 +1453,14 @@ static int check_extent_data_ref(struct extent_buffer *leaf, return -EUCLEAN; } for (; ptr < end; ptr += sizeof(*dref)) { - u64 root_objectid; - u64 owner; u64 offset; - u64 hash; + /* + * We cannot check the extent_data_ref hash due to possible + * overflow from the leaf due to hash collisions. + */ dref = (struct btrfs_extent_data_ref *)ptr; - root_objectid = btrfs_extent_data_ref_root(leaf, dref); - owner = btrfs_extent_data_ref_objectid(leaf, dref); offset = btrfs_extent_data_ref_offset(leaf, dref); - hash = hash_extent_data_ref(root_objectid, owner, offset); - if (unlikely(hash != key->offset)) { - extent_err(leaf, slot, - "invalid extent data ref hash, item has 0x%016llx key has 0x%016llx", - hash, key->offset); - return -EUCLEAN; - } if (unlikely(!IS_ALIGNED(offset, leaf->fs_info->sectorsize))) { extent_err(leaf, slot, "invalid extent data backref offset, have %llu expect aligned to %u",

3 years, 7 months

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FAILED: patch "[PATCH] btrfs: tree-checker: do not error out if extent ref hash" 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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 1119a72e223f3073a604f8fccb3a470ccd8a4416 Mon Sep 17 00:00:00 2001 From: Josef Bacik <josef(a)toxicpanda.com> Date: Tue, 16 Feb 2021 15:43:22 -0500 Subject: [PATCH] btrfs: tree-checker: do not error out if extent ref hash doesn't match MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The tree checker checks the extent ref hash at read and write time to make sure we do not corrupt the file system. Generally extent references go inline, but if we have enough of them we need to make an item, which looks like key.objectid = <bytenr> key.type = <BTRFS_EXTENT_DATA_REF_KEY|BTRFS_TREE_BLOCK_REF_KEY> key.offset = hash(tree, owner, offset) However if key.offset collide with an unrelated extent reference we'll simply key.offset++ until we get something that doesn't collide. Obviously this doesn't match at tree checker time, and thus we error while writing out the transaction. This is relatively easy to reproduce, simply do something like the following xfs_io -f -c "pwrite 0 1M" file offset=2 for i in {0..10000} do xfs_io -c "reflink file 0 ${offset}M 1M" file offset=$(( offset + 2 )) done xfs_io -c "reflink file 0 17999258914816 1M" file xfs_io -c "reflink file 0 35998517829632 1M" file xfs_io -c "reflink file 0 53752752058368 1M" file btrfs filesystem sync And the sync will error out because we'll abort the transaction. The magic values above are used because they generate hash collisions with the first file in the main subvol. The fix for this is to remove the hash value check from tree checker, as we have no idea which offset ours should belong to. Reported-by: Tuomas Lähdekorpi <tuomas.lahdekorpi(a)gmail.com> Fixes: 0785a9aacf9d ("btrfs: tree-checker: Add EXTENT_DATA_REF check") 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> Reviewed-by: David Sterba <dsterba(a)suse.com> [ add comment] Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index 582061c7b547..f4ade821307d 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -1453,22 +1453,14 @@ static int check_extent_data_ref(struct extent_buffer *leaf, return -EUCLEAN; } for (; ptr < end; ptr += sizeof(*dref)) { - u64 root_objectid; - u64 owner; u64 offset; - u64 hash; + /* + * We cannot check the extent_data_ref hash due to possible + * overflow from the leaf due to hash collisions. + */ dref = (struct btrfs_extent_data_ref *)ptr; - root_objectid = btrfs_extent_data_ref_root(leaf, dref); - owner = btrfs_extent_data_ref_objectid(leaf, dref); offset = btrfs_extent_data_ref_offset(leaf, dref); - hash = hash_extent_data_ref(root_objectid, owner, offset); - if (unlikely(hash != key->offset)) { - extent_err(leaf, slot, - "invalid extent data ref hash, item has 0x%016llx key has 0x%016llx", - hash, key->offset); - return -EUCLEAN; - } if (unlikely(!IS_ALIGNED(offset, leaf->fs_info->sectorsize))) { extent_err(leaf, slot, "invalid extent data backref offset, have %llu expect aligned to %u",

3 years, 7 months

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FAILED: patch "[PATCH] btrfs: fix stale data exposure after cloning a hole with" 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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 3660d0bcdb82807d434da9d2e57d88b37331182d Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Tue, 16 Feb 2021 11:09:25 +0000 Subject: [PATCH] btrfs: fix stale data exposure after cloning a hole with NO_HOLES enabled When using the NO_HOLES feature, if we clone a file range that spans only a hole into a range that is at or beyond the current i_size of the destination file, we end up not setting the full sync runtime flag on the inode. As a result, if we then fsync the destination file and have a power failure, after log replay we can end up exposing stale data instead of having a hole for that range. The conditions for this to happen are the following: 1) We have a file with a size of, for example, 1280K; 2) There is a written (non-prealloc) extent for the file range from 1024K to 1280K with a length of 256K; 3) This particular file extent layout is durably persisted, so that the existing superblock persisted on disk points to a subvolume root where the file has that exact file extent layout and state; 4) The file is truncated to a smaller size, to an offset lower than the start offset of its last extent, for example to 800K. The truncate sets the full sync runtime flag on the inode; 6) Fsync the file to log it and clear the full sync runtime flag; 7) Clone a region that covers only a hole (implicit hole due to NO_HOLES) into the file with a destination offset that starts at or beyond the 256K file extent item we had - for example to offset 1024K; 8) Since the clone operation does not find extents in the source range, we end up in the if branch at the bottom of btrfs_clone() where we punch a hole for the file range starting at offset 1024K by calling btrfs_replace_file_extents(). There we end up not setting the full sync flag on the inode, because we don't know we are being called in a clone context (and not fallocate's punch hole operation), and neither do we create an extent map to represent a hole because the requested range is beyond eof; 9) A further fsync to the file will be a fast fsync, since the clone operation did not set the full sync flag, and therefore it relies on modified extent maps to correctly log the file layout. But since it does not find any extent map marking the range from 1024K (the previous eof) to the new eof, it does not log a file extent item for that range representing the hole; 10) After a power failure no hole for the range starting at 1024K is punched and we end up exposing stale data from the old 256K extent. Turning this into exact steps: $ mkfs.btrfs -f -O no-holes /dev/sdi $ mount /dev/sdi /mnt # Create our test file with 3 extents of 256K and a 256K hole at offset # 256K. The file has a size of 1280K. $ xfs_io -f -s \ -c "pwrite -S 0xab -b 256K 0 256K" \ -c "pwrite -S 0xcd -b 256K 512K 256K" \ -c "pwrite -S 0xef -b 256K 768K 256K" \ -c "pwrite -S 0x73 -b 256K 1024K 256K" \ /mnt/sdi/foobar # Make sure it's durably persisted. We want the last committed super # block to point to this particular file extent layout. sync # Now truncate our file to a smaller size, falling within a position of # the second extent. This sets the full sync runtime flag on the inode. # Then fsync the file to log it and clear the full sync flag from the # inode. The third extent is no longer part of the file and therefore # it is not logged. $ xfs_io -c "truncate 800K" -c "fsync" /mnt/foobar # Now do a clone operation that only clones the hole and sets back the # file size to match the size it had before the truncate operation # (1280K). $ xfs_io \ -c "reflink /mnt/foobar 256K 1024K 256K" \ -c "fsync" \ /mnt/foobar # File data before power failure: $ od -A d -t x1 /mnt/foobar 0000000 ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab * 0262144 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 0524288 cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd * 0786432 ef ef ef ef ef ef ef ef ef ef ef ef ef ef ef ef * 0819200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 1310720 <power fail> # Mount the fs again to replay the log tree. $ mount /dev/sdi /mnt # File data after power failure: $ od -A d -t x1 /mnt/foobar 0000000 ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab ab * 0262144 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 0524288 cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd cd * 0786432 ef ef ef ef ef ef ef ef ef ef ef ef ef ef ef ef * 0819200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 * 1048576 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 * 1310720 The range from 1024K to 1280K should correspond to a hole but instead it points to stale data, to the 256K extent that should not exist after the truncate operation. The issue does not exists when not using NO_HOLES, because for that case we use file extent items to represent holes, these are found and copied during the loop that iterates over extents at btrfs_clone(), and that causes btrfs_replace_file_extents() to be called with a non-NULL extent_info argument and therefore set the full sync runtime flag on the inode. So fix this by making the code that deals with a trailing hole during cloning, at btrfs_clone(), to set the full sync flag on the inode, if the range starts at or beyond the current i_size. A test case for fstests will follow soon. Backporting notes: for kernel 5.4 the change goes to ioctl.c into btrfs_clone before the last call to btrfs_punch_hole_range. CC: stable(a)vger.kernel.org # 5.4+ Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c index b24396cf2f99..5413578d2c32 100644 --- a/fs/btrfs/reflink.c +++ b/fs/btrfs/reflink.c @@ -553,6 +553,24 @@ static int btrfs_clone(struct inode *src, struct inode *inode, */ btrfs_release_path(path); + /* + * When using NO_HOLES and we are cloning a range that covers + * only a hole (no extents) into a range beyond the current + * i_size, punching a hole in the target range will not create + * an extent map defining a hole, because the range starts at or + * beyond current i_size. If the file previously had an i_size + * greater than the new i_size set by this clone operation, we + * need to make sure the next fsync is a full fsync, so that it + * detects and logs a hole covering a range from the current + * i_size to the new i_size. If the clone range covers extents, + * besides a hole, then we know the full sync flag was already + * set by previous calls to btrfs_replace_file_extents() that + * replaced file extent items. + */ + if (last_dest_end >= i_size_read(inode)) + set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, + &BTRFS_I(inode)->runtime_flags); + ret = btrfs_replace_file_extents(inode, path, last_dest_end, destoff + len - 1, NULL, &trans); if (ret)

3 years, 7 months

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FAILED: patch "[PATCH] btrfs: fix race between swap file activation and snapshot" 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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From dd0734f2a866f9d619d4abf97c3d71bcdee40ea9 Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Fri, 5 Feb 2021 12:55:38 +0000 Subject: [PATCH] btrfs: fix race between swap file activation and snapshot creation When creating a snapshot we check if the current number of swap files, in the root, is non-zero, and if it is, we error out and warn that we can not create the snapshot because there are active swap files. However this is racy because when a task started activation of a swap file, another task might have started already snapshot creation and might have seen the counter for the number of swap files as zero. This means that after the swap file is activated we may end up with a snapshot of the same root successfully created, and therefore when the first write to the swap file happens it has to fall back into COW mode, which should never happen for active swap files. Basically what can happen is: 1) Task A starts snapshot creation and enters ioctl.c:create_snapshot(). There it sees that root->nr_swapfiles has a value of 0 so it continues; 2) Task B enters btrfs_swap_activate(). It is not aware that another task started snapshot creation but it did not finish yet. It increments root->nr_swapfiles from 0 to 1; 3) Task B checks that the file meets all requirements to be an active swap file - it has NOCOW set, there are no snapshots for the inode's root at the moment, no file holes, no reflinked extents, etc; 4) Task B returns success and now the file is an active swap file; 5) Task A commits the transaction to create the snapshot and finishes. The swap file's extents are now shared between the original root and the snapshot; 6) A write into an extent of the swap file is attempted - there is a snapshot of the file's root, so we fall back to COW mode and therefore the physical location of the extent changes on disk. So fix this by taking the snapshot lock during swap file activation before locking the extent range, as that is the order in which we lock these during buffered writes. Fixes: ed46ff3d42378 ("Btrfs: support swap files") CC: stable(a)vger.kernel.org # 5.4+ Reviewed-by: Anand Jain <anand.jain(a)oracle.com> Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 30358a2e2bc0..4f2f1e932751 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -10298,7 +10298,8 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file, sector_t *span) { struct inode *inode = file_inode(file); - struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info; + struct btrfs_root *root = BTRFS_I(inode)->root; + struct btrfs_fs_info *fs_info = root->fs_info; struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; struct extent_state *cached_state = NULL; struct extent_map *em = NULL; @@ -10349,13 +10350,27 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file, "cannot activate swapfile while exclusive operation is running"); return -EBUSY; } + + /* + * Prevent snapshot creation while we are activating the swap file. + * We do not want to race with snapshot creation. If snapshot creation + * already started before we bumped nr_swapfiles from 0 to 1 and + * completes before the first write into the swap file after it is + * activated, than that write would fallback to COW. + */ + if (!btrfs_drew_try_write_lock(&root->snapshot_lock)) { + btrfs_exclop_finish(fs_info); + btrfs_warn(fs_info, + "cannot activate swapfile because snapshot creation is in progress"); + return -EINVAL; + } /* * Snapshots can create extents which require COW even if NODATACOW is * set. We use this counter to prevent snapshots. We must increment it * before walking the extents because we don't want a concurrent * snapshot to run after we've already checked the extents. */ - atomic_inc(&BTRFS_I(inode)->root->nr_swapfiles); + atomic_inc(&root->nr_swapfiles); isize = ALIGN_DOWN(inode->i_size, fs_info->sectorsize); @@ -10501,6 +10516,8 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file, if (ret) btrfs_swap_deactivate(file); + btrfs_drew_write_unlock(&root->snapshot_lock); + btrfs_exclop_finish(fs_info); if (ret)

3 years, 7 months

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FAILED: patch "[PATCH] btrfs: fix race between writes to swap files and scrub" 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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 195a49eaf655eb914896c92cecd96bc863c9feb3 Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Fri, 5 Feb 2021 12:55:37 +0000 Subject: [PATCH] btrfs: fix race between writes to swap files and scrub When we active a swap file, at btrfs_swap_activate(), we acquire the exclusive operation lock to prevent the physical location of the swap file extents to be changed by operations such as balance and device replace/resize/remove. We also call there can_nocow_extent() which, among other things, checks if the block group of a swap file extent is currently RO, and if it is we can not use the extent, since a write into it would result in COWing the extent. However we have no protection against a scrub operation running after we activate the swap file, which can result in the swap file extents to be COWed while the scrub is running and operating on the respective block group, because scrub turns a block group into RO before it processes it and then back again to RW mode after processing it. That means an attempt to write into a swap file extent while scrub is processing the respective block group, will result in COWing the extent, changing its physical location on disk. Fix this by making sure that block groups that have extents that are used by active swap files can not be turned into RO mode, therefore making it not possible for a scrub to turn them into RO mode. When a scrub finds a block group that can not be turned to RO due to the existence of extents used by swap files, it proceeds to the next block group and logs a warning message that mentions the block group was skipped due to active swap files - this is the same approach we currently use for balance. Fixes: ed46ff3d42378 ("Btrfs: support swap files") CC: stable(a)vger.kernel.org # 5.4+ Reviewed-by: Anand Jain <anand.jain(a)oracle.com> Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index 5064be59dac5..744b99ddc28c 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1162,6 +1162,11 @@ static int inc_block_group_ro(struct btrfs_block_group *cache, int force) spin_lock(&sinfo->lock); spin_lock(&cache->lock); + if (cache->swap_extents) { + ret = -ETXTBSY; + goto out; + } + if (cache->ro) { cache->ro++; ret = 0; @@ -2307,7 +2312,7 @@ int btrfs_inc_block_group_ro(struct btrfs_block_group *cache, } ret = inc_block_group_ro(cache, 0); - if (!do_chunk_alloc) + if (!do_chunk_alloc || ret == -ETXTBSY) goto unlock_out; if (!ret) goto out; @@ -2316,6 +2321,8 @@ int btrfs_inc_block_group_ro(struct btrfs_block_group *cache, if (ret < 0) goto out; ret = inc_block_group_ro(cache, 0); + if (ret == -ETXTBSY) + goto unlock_out; out: if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) { alloc_flags = btrfs_get_alloc_profile(fs_info, cache->flags); @@ -3406,6 +3413,7 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info) ASSERT(list_empty(&block_group->io_list)); ASSERT(list_empty(&block_group->bg_list)); ASSERT(refcount_read(&block_group->refs) == 1); + ASSERT(block_group->swap_extents == 0); btrfs_put_block_group(block_group); spin_lock(&info->block_group_cache_lock); @@ -3472,3 +3480,26 @@ void btrfs_unfreeze_block_group(struct btrfs_block_group *block_group) __btrfs_remove_free_space_cache(block_group->free_space_ctl); } } + +bool btrfs_inc_block_group_swap_extents(struct btrfs_block_group *bg) +{ + bool ret = true; + + spin_lock(&bg->lock); + if (bg->ro) + ret = false; + else + bg->swap_extents++; + spin_unlock(&bg->lock); + + return ret; +} + +void btrfs_dec_block_group_swap_extents(struct btrfs_block_group *bg, int amount) +{ + spin_lock(&bg->lock); + ASSERT(!bg->ro); + ASSERT(bg->swap_extents >= amount); + bg->swap_extents -= amount; + spin_unlock(&bg->lock); +} diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h index 29678426247d..3ecc3372a5ce 100644 --- a/fs/btrfs/block-group.h +++ b/fs/btrfs/block-group.h @@ -186,6 +186,12 @@ struct btrfs_block_group { /* Flag indicating this block group is placed on a sequential zone */ bool seq_zone; + /* + * Number of extents in this block group used for swap files. + * All accesses protected by the spinlock 'lock'. + */ + int swap_extents; + /* Record locked full stripes for RAID5/6 block group */ struct btrfs_full_stripe_locks_tree full_stripe_locks_root; @@ -312,4 +318,7 @@ static inline int btrfs_block_group_done(struct btrfs_block_group *cache) void btrfs_freeze_block_group(struct btrfs_block_group *cache); void btrfs_unfreeze_block_group(struct btrfs_block_group *cache); +bool btrfs_inc_block_group_swap_extents(struct btrfs_block_group *bg); +void btrfs_dec_block_group_swap_extents(struct btrfs_block_group *bg, int amount); + #endif /* BTRFS_BLOCK_GROUP_H */ diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 3bc00aed13b2..40ec3393d2a1 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -524,6 +524,11 @@ struct btrfs_swapfile_pin { * points to a struct btrfs_device. */ bool is_block_group; + /* + * Only used when 'is_block_group' is true and it is the number of + * extents used by a swapfile for this block group ('ptr' field). + */ + int bg_extent_count; }; bool btrfs_pinned_by_swapfile(struct btrfs_fs_info *fs_info, void *ptr); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index d6f0e1ad3711..30358a2e2bc0 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -10192,6 +10192,7 @@ static int btrfs_add_swapfile_pin(struct inode *inode, void *ptr, sp->ptr = ptr; sp->inode = inode; sp->is_block_group = is_block_group; + sp->bg_extent_count = 1; spin_lock(&fs_info->swapfile_pins_lock); p = &fs_info->swapfile_pins.rb_node; @@ -10205,6 +10206,8 @@ static int btrfs_add_swapfile_pin(struct inode *inode, void *ptr, (sp->ptr == entry->ptr && sp->inode > entry->inode)) { p = &(*p)->rb_right; } else { + if (is_block_group) + entry->bg_extent_count++; spin_unlock(&fs_info->swapfile_pins_lock); kfree(sp); return 1; @@ -10230,8 +10233,11 @@ static void btrfs_free_swapfile_pins(struct inode *inode) sp = rb_entry(node, struct btrfs_swapfile_pin, node); if (sp->inode == inode) { rb_erase(&sp->node, &fs_info->swapfile_pins); - if (sp->is_block_group) + if (sp->is_block_group) { + btrfs_dec_block_group_swap_extents(sp->ptr, + sp->bg_extent_count); btrfs_put_block_group(sp->ptr); + } kfree(sp); } node = next; @@ -10446,6 +10452,17 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file, goto out; } + if (!btrfs_inc_block_group_swap_extents(bg)) { + btrfs_warn(fs_info, + "block group for swapfile at %llu is read-only%s", + bg->start, + atomic_read(&fs_info->scrubs_running) ? + " (scrub running)" : ""); + btrfs_put_block_group(bg); + ret = -EINVAL; + goto out; + } + ret = btrfs_add_swapfile_pin(inode, bg, true); if (ret) { btrfs_put_block_group(bg); diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 310fce00fcda..70a90ca2c8da 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -3767,6 +3767,13 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx, * commit_transactions. */ ro_set = 0; + } else if (ret == -ETXTBSY) { + btrfs_warn(fs_info, + "skipping scrub of block group %llu due to active swapfile", + cache->start); + scrub_pause_off(fs_info); + ret = 0; + goto skip_unfreeze; } else { btrfs_warn(fs_info, "failed setting block group ro: %d", ret); @@ -3862,7 +3869,7 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx, } else { spin_unlock(&cache->lock); } - +skip_unfreeze: btrfs_unfreeze_block_group(cache); btrfs_put_block_group(cache); if (ret)

3 years, 7 months

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FAILED: patch "[PATCH] btrfs: avoid double put of block group when emptying cluster" 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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 95c85fba1f64c3249c67f0078a29f8a125078189 Mon Sep 17 00:00:00 2001 From: Josef Bacik <josef(a)toxicpanda.com> Date: Mon, 25 Jan 2021 16:42:35 -0500 Subject: [PATCH] btrfs: avoid double put of block group when emptying cluster It's wrong calling btrfs_put_block_group in __btrfs_return_cluster_to_free_space if the block group passed is different than the block group the cluster represents. As this means the cluster doesn't have a reference to the passed block group. This results in double put and a use-after-free bug. Fix this by simply bailing if the block group we passed in does not match the block group on the cluster. Fixes: fa9c0d795f7b ("Btrfs: rework allocation clustering") CC: stable(a)vger.kernel.org # 4.4+ Signed-off-by: Josef Bacik <josef(a)toxicpanda.com> Reviewed-by: David Sterba <dsterba(a)suse.com> [ update changelog ] Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index abcf951e6b44..711a6a751ae9 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -2801,8 +2801,10 @@ static void __btrfs_return_cluster_to_free_space( struct rb_node *node; spin_lock(&cluster->lock); - if (cluster->block_group != block_group) - goto out; + if (cluster->block_group != block_group) { + spin_unlock(&cluster->lock); + return; + } cluster->block_group = NULL; cluster->window_start = 0; @@ -2840,8 +2842,6 @@ static void __btrfs_return_cluster_to_free_space( entry->offset, &entry->offset_index, bitmap); } cluster->root = RB_ROOT; - -out: spin_unlock(&cluster->lock); btrfs_put_block_group(block_group); }

3 years, 7 months

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FAILED: patch "[PATCH] btrfs: avoid double put of block group when emptying cluster" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-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>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 95c85fba1f64c3249c67f0078a29f8a125078189 Mon Sep 17 00:00:00 2001 From: Josef Bacik <josef(a)toxicpanda.com> Date: Mon, 25 Jan 2021 16:42:35 -0500 Subject: [PATCH] btrfs: avoid double put of block group when emptying cluster It's wrong calling btrfs_put_block_group in __btrfs_return_cluster_to_free_space if the block group passed is different than the block group the cluster represents. As this means the cluster doesn't have a reference to the passed block group. This results in double put and a use-after-free bug. Fix this by simply bailing if the block group we passed in does not match the block group on the cluster. Fixes: fa9c0d795f7b ("Btrfs: rework allocation clustering") CC: stable(a)vger.kernel.org # 4.4+ Signed-off-by: Josef Bacik <josef(a)toxicpanda.com> Reviewed-by: David Sterba <dsterba(a)suse.com> [ update changelog ] Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index abcf951e6b44..711a6a751ae9 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -2801,8 +2801,10 @@ static void __btrfs_return_cluster_to_free_space( struct rb_node *node; spin_lock(&cluster->lock); - if (cluster->block_group != block_group) - goto out; + if (cluster->block_group != block_group) { + spin_unlock(&cluster->lock); + return; + } cluster->block_group = NULL; cluster->window_start = 0; @@ -2840,8 +2842,6 @@ static void __btrfs_return_cluster_to_free_space( entry->offset, &entry->offset_index, bitmap); } cluster->root = RB_ROOT; - -out: spin_unlock(&cluster->lock); btrfs_put_block_group(block_group); }

3 years, 7 months

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