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| author | Josef Bacik <jbacik@fb.com> | 2014-09-10 16:20:45 -0400 |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2014-09-17 13:38:24 -0700 |
| commit | dc046b10c8b7d4f40befe457acb82340bf8b0699 (patch) | |
| tree | 2659e92649b19df4cd54a65eabd34f961f8d57f8 /fs/btrfs/backref.h | |
| parent | 78a017a2c92df9b571db0a55a016280f9019c65e (diff) | |
| download | lwn-dc046b10c8b7d4f40befe457acb82340bf8b0699.tar.gz lwn-dc046b10c8b7d4f40befe457acb82340bf8b0699.zip | |
Btrfs: make fiemap not blow when you have lots of snapshots
We have been iterating all references for each extent we have in a file when we
do fiemap to see if it is shared. This is fine when you have a few clones or a
few snapshots, but when you have 5k snapshots suddenly fiemap just sits there
and stares at you. So add btrfs_check_shared which will use the backref walking
code but will short circuit as soon as it finds a root or inode that doesn't
match the one we currently have. This makes fiemap on my testbox go from
looking at me blankly for a day to spitting out actual output in a reasonable
amount of time. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs/backref.h')
| -rw-r--r-- | fs/btrfs/backref.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h index 86fc20fec282..2a1ac6bfc724 100644 --- a/fs/btrfs/backref.h +++ b/fs/btrfs/backref.h @@ -71,6 +71,9 @@ int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid, u64 start_off, struct btrfs_path *path, struct btrfs_inode_extref **ret_extref, u64 *found_off); +int btrfs_check_shared(struct btrfs_trans_handle *trans, + struct btrfs_fs_info *fs_info, u64 root_objectid, + u64 inum, u64 bytenr); int __init btrfs_prelim_ref_init(void); void btrfs_prelim_ref_exit(void); |