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authorFilipe Manana <fdmanana@suse.com>2015-05-05 15:21:27 +0100
committerChris Mason <clm@fb.com>2015-05-11 07:59:10 -0700
commite43699d4b4c5d9ecbcb5998cdcbada060981171f (patch)
tree710a6440afd5503acc5234802b7f4369ec8d4600 /fs
parent1d3c61c2eb3fe4f96d3192212f1bdcee49ea55aa (diff)
downloadkernel-e43699d4b4c5d9ecbcb5998cdcbada060981171f.tar.gz
Btrfs: fix crash after inode cache writeback failure
If the writeback of an inode cache failed we were unnecessarilly attempting to release again the delalloc metadata that we previously reserved. However attempting to do this a second time triggers an assertion at drop_outstanding_extent() because we have no more outstanding extents for our inode cache's inode. If we were able to start writeback of the cache the reserved metadata space is released at btrfs_finished_ordered_io(), even if an error happens during writeback. So make sure we don't repeat the metadata space release if writeback started for our inode cache. This issue was trivial to reproduce by running the fstest btrfs/088 with "-o inode_cache", which triggered the assertion leading to a BUG() call and requiring a reboot in order to run the remaining fstests. Trace produced by btrfs/088: [255289.385904] BTRFS: assertion failed: BTRFS_I(inode)->outstanding_extents >= num_extents, file: fs/btrfs/extent-tree.c, line: 5276 [255289.388094] ------------[ cut here ]------------ [255289.389184] kernel BUG at fs/btrfs/ctree.h:4057! [255289.390125] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC (...) [255289.392068] Call Trace: [255289.392068] [<ffffffffa035e774>] drop_outstanding_extent+0x3d/0x6d [btrfs] [255289.392068] [<ffffffffa0364988>] btrfs_delalloc_release_metadata+0x54/0xe3 [btrfs] [255289.392068] [<ffffffffa03b4174>] btrfs_write_out_ino_cache+0x95/0xad [btrfs] [255289.392068] [<ffffffffa036f5c4>] btrfs_save_ino_cache+0x275/0x2dc [btrfs] [255289.392068] [<ffffffffa03e2d83>] commit_fs_roots.isra.12+0xaa/0x137 [btrfs] [255289.392068] [<ffffffff8107d33d>] ? trace_hardirqs_on+0xd/0xf [255289.392068] [<ffffffffa037841f>] ? btrfs_commit_transaction+0x4b1/0x9c9 [btrfs] [255289.392068] [<ffffffff814351a4>] ? _raw_spin_unlock+0x32/0x46 [255289.392068] [<ffffffffa037842e>] btrfs_commit_transaction+0x4c0/0x9c9 [btrfs] (...) Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/free-space-cache.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 5e020d76fd07..9dbe5b548fa6 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -3466,6 +3466,7 @@ int btrfs_write_out_ino_cache(struct btrfs_root *root,
struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
int ret;
struct btrfs_io_ctl io_ctl;
+ bool release_metadata = true;
if (!btrfs_test_opt(root, INODE_MAP_CACHE))
return 0;
@@ -3473,11 +3474,20 @@ int btrfs_write_out_ino_cache(struct btrfs_root *root,
memset(&io_ctl, 0, sizeof(io_ctl));
ret = __btrfs_write_out_cache(root, inode, ctl, NULL, &io_ctl,
trans, path, 0);
- if (!ret)
+ if (!ret) {
+ /*
+ * At this point writepages() didn't error out, so our metadata
+ * reservation is released when the writeback finishes, at
+ * inode.c:btrfs_finish_ordered_io(), regardless of it finishing
+ * with or without an error.
+ */
+ release_metadata = false;
ret = btrfs_wait_cache_io(root, trans, NULL, &io_ctl, path, 0);
+ }
if (ret) {
- btrfs_delalloc_release_metadata(inode, inode->i_size);
+ if (release_metadata)
+ btrfs_delalloc_release_metadata(inode, inode->i_size);
#ifdef DEBUG
btrfs_err(root->fs_info,
"failed to write free ino cache for root %llu",