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Btrfs: fix unlock after free on rewinded tree blocks 

When tree_mod_log_rewind decides to make a copy of the current tree buffer
for its modifications, it subsequently freed the buffer before unlocking it.
Obviously, those operations are required in reverse order.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This commit is contained in:
Jan Schmidt 2013-04-13 13:19:55 +00:00 committed by Josef Bacik
parent 30b0463a93
commit 47fb091fb7
1 changed files with 11 additions and 7 deletions
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18
fs/btrfs/ctree.c
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@ -1191,6 +1191,13 @@ __tree_mod_log_rewind(struct extent_buffer *eb, u64 time_seq,
btrfs_set_header_nritems(eb, n);
}
/*
* Called with eb read locked. If the buffer cannot be rewinded, the same buffer
* is returned. If rewind operations happen, a fresh buffer is returned. The
* returned buffer is always read-locked. If the returned buffer is not the
* input buffer, the lock on the input buffer is released and the input buffer
* is freed (its refcount is decremented).
*/
static struct extent_buffer *
tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
u64 time_seq)
@ -1224,8 +1231,11 @@ tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
}
extent_buffer_get(eb_rewin);
btrfs_tree_read_unlock(eb);
free_extent_buffer(eb);
extent_buffer_get(eb_rewin);
btrfs_tree_read_lock(eb_rewin);
__tree_mod_log_rewind(eb_rewin, time_seq, tm);
WARN_ON(btrfs_header_nritems(eb_rewin) >
BTRFS_NODEPTRS_PER_BLOCK(fs_info->tree_root));
@ -2794,15 +2804,9 @@ again:
btrfs_clear_path_blocking(p, b,
BTRFS_READ_LOCK);
}
b = tree_mod_log_rewind(root->fs_info, b, time_seq);
p->locks[level] = BTRFS_READ_LOCK;
p->nodes[level] = b;
b = tree_mod_log_rewind(root->fs_info, b, time_seq);
if (b != p->nodes[level]) {
btrfs_tree_unlock_rw(p->nodes[level],
p->locks[level]);
p->locks[level] = 0;
p->nodes[level] = b;
}
} else {
p->slots[level] = slot;
unlock_up(p, level, lowest_unlock, 0, NULL);