diff options
| author | Lu Fengqi <lufq.fnst@cn.fujitsu.com> | 2016-06-13 09:36:46 +0800 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2016-09-26 17:59:49 +0200 |
| commit | afce772e87c36c7f07f230a76d525025aaf09e41 (patch) | |
| tree | 544c9365efd38bea2356fde31592be01a56576eb /fs/btrfs/extent_io.c | |
| parent | b0de6c4c81099494d7863a31db06366f74395cda (diff) | |
btrfs: fix check_shared for fiemap ioctl
Only in the case of different root_id or different object_id, check_shared
identified extent as the shared. However, If a extent was referred by
different offset of same file, it should also be identified as shared.
In addition, check_shared's loop scale is at least n^3, so if a extent
has too many references, even causes soft hang up.
First, add all delayed_ref to the ref_tree and calculate the unqiue_refs,
if the unique_refs is greater than one, return BACKREF_FOUND_SHARED.
Then individually add the on-disk reference(inline/keyed) to the ref_tree
and calculate the unique_refs of the ref_tree to check if the unique_refs
is greater than one.Because once there are two references to return
SHARED, so the time complexity is close to the constant.
Reported-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/extent_io.c')
| -rw-r--r-- | fs/btrfs/extent_io.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 44fe66b53c8b..8644df8ba527 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -20,6 +20,7 @@ #include "locking.h" #include "rcu-string.h" #include "backref.h" +#include "transaction.h" static struct kmem_cache *extent_state_cache; static struct kmem_cache *extent_buffer_cache; @@ -4487,21 +4488,36 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, flags |= (FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN); } else if (fieinfo->fi_extents_max) { + struct btrfs_trans_handle *trans; + u64 bytenr = em->block_start - (em->start - em->orig_start); disko = em->block_start + offset_in_extent; /* + * We need a trans handle to get delayed refs + */ + trans = btrfs_join_transaction(root); + /* + * It's OK if we can't start a trans we can still check + * from commit_root + */ + if (IS_ERR(trans)) + trans = NULL; + + /* * As btrfs supports shared space, this information * can be exported to userspace tools via * flag FIEMAP_EXTENT_SHARED. If fi_extents_max == 0 * then we're just getting a count and we can skip the * lookup stuff. */ - ret = btrfs_check_shared(NULL, root->fs_info, + ret = btrfs_check_shared(trans, root->fs_info, root->objectid, btrfs_ino(inode), bytenr); + if (trans) + btrfs_end_transaction(trans, root); if (ret < 0) goto out_free; if (ret) |