From: Filipe Manana fdmanana@suse.com
[ Upstream commit 72c3668fed2b3eec7c6fc059e7b54855361e3011 ]
Currently an incremental snapshot can generate link operations which contain an invalid target path. Such case happens when in the send snapshot a file was renamed, a new hard link added for it and some other inode (with a lower number) got renamed to the former name of that file. Example:
Parent snapshot
. (ino 256) | |--- f1 (ino 257) |--- f2 (ino 258) |--- f3 (ino 259)
Send snapshot
. (ino 256) | |--- f2 (ino 257) |--- f3 (ino 258) |--- f4 (ino 259) |--- f5 (ino 258)
The following steps happen when computing the incremental send stream:
1) When processing inode 257, inode 258 is orphanized (renamed to "o258-7-0"), because its current reference has the same name as the new reference for inode 257;
2) When processing inode 258, we iterate over all its new references, which have the names "f3" and "f5". The first iteration sees name "f5" and renames the inode from its orphan name ("o258-7-0") to "f5", while the second iteration sees the name "f3" and, incorrectly, issues a link operation with a target name matching the orphan name, which no longer exists. The first iteration had reset the current valid path of the inode to "f5", but in the second iteration we lost it because we found another inode, with a higher number of 259, which has a reference named "f3" as well, so we orphanized inode 259 and recomputed the current valid path of inode 258 to its old orphan name because inode 259 could be an ancestor of inode 258 and therefore the current valid path could contain the pre-orphanization name of inode 259. However in this case inode 259 is not an ancestor of inode 258 so the current valid path should not be recomputed. This makes the receiver fail with the following error:
ERROR: link f3 -> o258-7-0 failed: No such file or directory
So fix this by not recomputing the current valid path for an inode whenever we find a colliding reference from some not yet processed inode (inode number higher then the one currently being processed), unless that other inode is an ancestor of the one we are currently processing.
A test case for fstests will follow soon.
Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- fs/btrfs/send.c | 35 +++++++++++++++++++++++++++-------- 1 file changed, 27 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index d040afc966fe..c3836978967c 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -3531,9 +3531,17 @@ static int is_ancestor(struct btrfs_root *root, struct fs_path *fs_path) { u64 ino = ino2; + bool free_path = false; + int ret = 0; + + if (!fs_path) { + fs_path = fs_path_alloc(); + if (!fs_path) + return -ENOMEM; + free_path = true; + }
while (ino > BTRFS_FIRST_FREE_OBJECTID) { - int ret; u64 parent; u64 parent_gen;
@@ -3542,13 +3550,18 @@ static int is_ancestor(struct btrfs_root *root, if (ret < 0) { if (ret == -ENOENT && ino == ino2) ret = 0; - return ret; + goto out; + } + if (parent == ino1) { + ret = parent_gen == ino1_gen ? 1 : 0; + goto out; } - if (parent == ino1) - return parent_gen == ino1_gen ? 1 : 0; ino = parent; } - return 0; + out: + if (free_path) + fs_path_free(fs_path); + return ret; }
static int wait_for_parent_move(struct send_ctx *sctx, @@ -3809,9 +3822,15 @@ static int process_recorded_refs(struct send_ctx *sctx, int *pending_move) * might contain the pre-orphanization name of * ow_inode, which is no longer valid. */ - fs_path_reset(valid_path); - ret = get_cur_path(sctx, sctx->cur_ino, - sctx->cur_inode_gen, valid_path); + ret = is_ancestor(sctx->parent_root, + ow_inode, ow_gen, + sctx->cur_ino, NULL); + if (ret > 0) { + fs_path_reset(valid_path); + ret = get_cur_path(sctx, sctx->cur_ino, + sctx->cur_inode_gen, + valid_path); + } if (ret < 0) goto out; } else {