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Btrfs: part 2, fix incremental send's decision to delay a dir move/rename

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For an incremental send, fix the process of determining whether the directory
inode we're currently processing needs to have its move/rename operation delayed.

We were ignoring the fact that if the inode's new immediate ancestor has a higher
inode number than ours but wasn't renamed/moved, we might still need to delay our
move/rename, because some other ancestor directory higher in the hierarchy might
have an inode number higher than ours *and* was renamed/moved too - in this case
we have to wait for rename/move of that ancestor to happen before our current
directory's rename/move operation.

Simple steps to reproduce this issue:

      $ mkfs.btrfs -f /dev/sdd
      $ mount /dev/sdd /mnt

      $ mkdir -p /mnt/a/x1/x2
      $ mkdir /mnt/a/Z
      $ mkdir -p /mnt/a/x1/x2/x3/x4/x5

      $ btrfs subvolume snapshot -r /mnt /mnt/snap1
      $ btrfs send /mnt/snap1 -f /tmp/base.send

      $ mv /mnt/a/x1/x2/x3 /mnt/a/Z/X33
      $ mv /mnt/a/x1/x2 /mnt/a/Z/X33/x4/x5/X22

      $ btrfs subvolume snapshot -r /mnt /mnt/snap2
      $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send

The incremental send caused the kernel code to enter an infinite loop when
building the path string for directory Z after its references are processed.

A more complex scenario:

      $ mkfs.btrfs -f /dev/sdd
      $ mount /dev/sdd /mnt

      $ mkdir -p /mnt/a/b/c/d
      $ mkdir /mnt/a/b/c/d/e
      $ mkdir /mnt/a/b/c/d/f
      $ mv /mnt/a/b/c/d/e /mnt/a/b/c/d/f/E2
      $ mkdir /mmt/a/b/c/g
      $ mv /mnt/a/b/c/d /mnt/a/b/D2

      $ btrfs subvolume snapshot -r /mnt /mnt/snap1
      $ btrfs send /mnt/snap1 -f /tmp/base.send

      $ mkdir /mnt/a/o
      $ mv /mnt/a/b/c/g /mnt/a/b/D2/f/G2
      $ mv /mnt/a/b/D2 /mnt/a/b/dd
      $ mv /mnt/a/b/c /mnt/a/C2
      $ mv /mnt/a/b/dd/f /mnt/a/o/FF
      $ mv /mnt/a/b /mnt/a/o/FF/E2/BB

      $ btrfs subvolume snapshot -r /mnt /mnt/snap2
      $ btrfs send -p /mnt/snap1 /mnt/snap2 -f /tmp/incremental.send

A test case for xfstests follows.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Filipe Manana 2014-03-19 14:20:54 +00:00 committed by Chris Mason
parent 7b119a8b89
commit bfa7e1f8be
1 changed files with 66 additions and 5 deletions
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71
fs/btrfs/send.c
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@ -2916,7 +2916,10 @@ static void free_waiting_dir_move(struct send_ctx *sctx,
kfree(dm);
}
static int add_pending_dir_move(struct send_ctx *sctx, u64 parent_ino)
static int add_pending_dir_move(struct send_ctx *sctx,
u64 ino,
u64 ino_gen,
u64 parent_ino)
{
struct rb_node **p = &sctx->pending_dir_moves.rb_node;
struct rb_node *parent = NULL;
@ -2929,8 +2932,8 @@ static int add_pending_dir_move(struct send_ctx *sctx, u64 parent_ino)
if (!pm)
return -ENOMEM;
pm->parent_ino = parent_ino;
pm->ino = sctx->cur_ino;
pm->gen = sctx->cur_inode_gen;
pm->ino = ino;
pm->gen = ino_gen;
INIT_LIST_HEAD(&pm->list);
INIT_LIST_HEAD(&pm->update_refs);
RB_CLEAR_NODE(&pm->node);
@ -3183,6 +3186,8 @@ static int wait_for_parent_move(struct send_ctx *sctx,
struct fs_path *path_before = NULL;
struct fs_path *path_after = NULL;
int len1, len2;
int register_upper_dirs;
u64 gen;
if (is_waiting_for_move(sctx, ino))
return 1;
@ -3220,7 +3225,7 @@ static int wait_for_parent_move(struct send_ctx *sctx,
}
ret = get_first_ref(sctx->send_root, ino, &parent_ino_after,
NULL, path_after);
&gen, path_after);
if (ret == -ENOENT) {
ret = 0;
goto out;
@ -3237,6 +3242,60 @@ static int wait_for_parent_move(struct send_ctx *sctx,
}
ret = 0;
/*
* Ok, our new most direct ancestor has a higher inode number but
* wasn't moved/renamed. So maybe some of the new ancestors higher in
* the hierarchy have an higher inode number too *and* were renamed
* or moved - in this case we need to wait for the ancestor's rename
* or move operation before we can do the move/rename for the current
* inode.
*/
register_upper_dirs = 0;
ino = parent_ino_after;
again:
while ((ret == 0 || register_upper_dirs) && ino > sctx->cur_ino) {
u64 parent_gen;
fs_path_reset(path_before);
fs_path_reset(path_after);
ret = get_first_ref(sctx->send_root, ino, &parent_ino_after,
&parent_gen, path_after);
if (ret < 0)
goto out;
ret = get_first_ref(sctx->parent_root, ino, &parent_ino_before,
NULL, path_before);
if (ret == -ENOENT) {
ret = 0;
break;
} else if (ret < 0) {
goto out;
}
len1 = fs_path_len(path_before);
len2 = fs_path_len(path_after);
if (parent_ino_before != parent_ino_after || len1 != len2 ||
memcmp(path_before->start, path_after->start, len1)) {
ret = 1;
if (register_upper_dirs) {
break;
} else {
register_upper_dirs = 1;
ino = parent_ref->dir;
gen = parent_ref->dir_gen;
goto again;
}
} else if (register_upper_dirs) {
ret = add_pending_dir_move(sctx, ino, gen,
parent_ino_after);
if (ret < 0 && ret != -EEXIST)
goto out;
}
ino = parent_ino_after;
gen = parent_gen;
}
out:
fs_path_free(path_before);
fs_path_free(path_after);
@ -3402,7 +3461,9 @@ verbose_printk("btrfs: process_recorded_refs %llu\n", sctx->cur_ino);
goto out;
if (ret) {
ret = add_pending_dir_move(sctx,
cur->dir);
sctx->cur_ino,
sctx->cur_inode_gen,
cur->dir);
*pending_move = 1;
} else {
ret = send_rename(sctx, valid_path,