@@ -1580,20 +1580,21 @@ int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
/**
* btrfs_check_shared - tell us whether an extent is shared
*
- * @trans: optional trans handle
- *
* btrfs_check_shared uses the backref walking code but will short
* circuit as soon as it finds a root or inode that doesn't match the
* one passed in. This provides a significant performance benefit for
* callers (such as fiemap) which want to know whether the extent is
* shared but do not need a ref count.
*
+ * This attempts to allocate a transaction in order to account for
+ * delayed refs, but continues on even when the alloc fails.
+ *
* Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
*/
-int btrfs_check_shared(struct btrfs_trans_handle *trans,
- struct btrfs_fs_info *fs_info, u64 root_objectid,
- u64 inum, u64 bytenr)
+int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_trans_handle *trans;
struct ulist *tmp = NULL;
struct ulist *roots = NULL;
struct ulist_iterator uiter;
@@ -1609,14 +1610,18 @@ int btrfs_check_shared(struct btrfs_trans_handle *trans,
return -ENOMEM;
}
- if (trans)
- btrfs_get_tree_mod_seq(fs_info, &elem);
- else
+ trans = btrfs_join_transaction(root);
+ if (IS_ERR(trans)) {
+ trans = NULL;
down_read(&fs_info->commit_root_sem);
+ } else {
+ btrfs_get_tree_mod_seq(fs_info, &elem);
+ }
+
ULIST_ITER_INIT(&uiter);
while (1) {
ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
- roots, NULL, root_objectid, inum, 1);
+ roots, NULL, root->objectid, inum, 1);
if (ret == BACKREF_FOUND_SHARED) {
/* this is the only condition under which we return 1 */
ret = 1;
@@ -1631,10 +1636,13 @@ int btrfs_check_shared(struct btrfs_trans_handle *trans,
bytenr = node->val;
cond_resched();
}
- if (trans)
+
+ if (trans) {
btrfs_put_tree_mod_seq(fs_info, &elem);
- else
+ btrfs_end_transaction(trans);
+ } else {
up_read(&fs_info->commit_root_sem);
+ }
ulist_free(tmp);
ulist_free(roots);
return ret;
@@ -68,9 +68,7 @@ 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 btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr);
int __init btrfs_prelim_ref_init(void);
void btrfs_prelim_ref_exit(void);
@@ -20,7 +20,6 @@
#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;
@@ -4606,36 +4605,21 @@ 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(trans, root->fs_info,
- root->objectid,
- btrfs_ino(BTRFS_I(inode)), bytenr);
- if (trans)
- btrfs_end_transaction(trans);
+ ret = btrfs_check_shared(root,
+ btrfs_ino(BTRFS_I(inode)),
+ bytenr);
if (ret < 0)
goto out_free;
if (ret)
Commit afce772e87c3 ("btrfs: fix check_shared for fiemap ioctl") added transaction semantics around calls to btrfs_check_shared() in order to provide accurate accounting of delayed refs. The transaction management should be done inside btrfs_check_shared(), so that callers do not need to manage transactions individually. Signed-off-by: Edmund Nadolski <enadolski@suse.com> Signed-off-by: Jeff Mahoney <jeffm@suse.com> --- fs/btrfs/backref.c | 30 +++++++++++++++++++----------- fs/btrfs/backref.h | 4 +--- fs/btrfs/extent_io.c | 22 +++------------------- 3 files changed, 23 insertions(+), 33 deletions(-)