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author | Filipe Manana <fdmanana@suse.com> | 2014-10-13 12:28:37 +0100 |
---|---|---|
committer | Chris Mason <clm@fb.com> | 2014-11-20 17:14:29 -0800 |
commit | 663dfbb07774e0fe1049e8db3054a08500122f18 (patch) | |
tree | f53b64787cf8b9221472bc4474f3c9fce75b605c /fs/btrfs/transaction.h | |
parent | 2fc9f6baa24ac230166df41ed636224969523341 (diff) | |
download | linux-663dfbb07774e0fe1049e8db3054a08500122f18.tar.bz2 |
Btrfs: deal with convert_extent_bit errors to avoid fs corruption
When committing a transaction or a log, we look for btree extents that
need to be durably persisted by searching for ranges in a io tree that
have some bits set (EXTENT_DIRTY or EXTENT_NEW). We then attempt to clear
those bits and set the EXTENT_NEED_WAIT bit, with calls to the function
convert_extent_bit, and then start writeback for the extents.
That function however can return an error (at the moment only -ENOMEM
is possible, specially when it does GFP_ATOMIC allocation requests
through alloc_extent_state_atomic) - that means the ranges didn't got
the EXTENT_NEED_WAIT bit set (or at least not for the whole range),
which in turn means a call to btrfs_wait_marked_extents() won't find
those ranges for which we started writeback, causing a transaction
commit or a log commit to persist a new superblock without waiting
for the writeback of extents in that range to finish first.
Therefore if a crash happens after persisting the new superblock and
before writeback finishes, we have a superblock pointing to roots that
weren't fully persisted or roots that point to nodes or leafs that weren't
fully persisted, causing all sorts of unexpected/bad behaviour as we endup
reading garbage from disk or the content of some node/leaf from a past
generation that got cowed or deleted and is no longer valid (for this later
case we end up getting error messages like "parent transid verify failed on
X wanted Y found Z" when reading btree nodes/leafs from disk).
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs/transaction.h')
-rw-r--r-- | fs/btrfs/transaction.h | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h index d8f40e1a5d2d..b3f5b40aab22 100644 --- a/fs/btrfs/transaction.h +++ b/fs/btrfs/transaction.h @@ -145,8 +145,6 @@ struct btrfs_trans_handle *btrfs_attach_transaction_barrier( struct btrfs_root *root); struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root); int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid); -int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans, - struct btrfs_root *root); void btrfs_add_dead_root(struct btrfs_root *root); int btrfs_defrag_root(struct btrfs_root *root); |