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authorLu Fengqi <lufq.fnst@cn.fujitsu.com>2016-06-13 09:36:46 +0800
committerDavid Sterba <dsterba@suse.com>2016-09-26 17:59:49 +0200
commitafce772e87c36c7f07f230a76d525025aaf09e41 (patch)
tree544c9365efd38bea2356fde31592be01a56576eb /fs/btrfs/extent_io.c
parentb0de6c4c81099494d7863a31db06366f74395cda (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.c18
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)