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authorFilipe Manana <fdmanana@suse.com>2014-08-04 22:37:21 +0400
committerChris Mason <clm@fb.com>2014-09-18 00:38:02 +0400
commitf98de9b9c07485f7e21edfd5b2b20c89d662af3c (patch)
treecf83b225c48c5f3fa32be73c25ad4c20b087d580 /fs/btrfs/ctree.c
parent79aec2b80db1089f983d60e4a22cb95d8b939844 (diff)
downloadlinux-f98de9b9c07485f7e21edfd5b2b20c89d662af3c.tar.xz
Btrfs: make btrfs_search_forward return with nodes unlocked
None of the uses of btrfs_search_forward() need to have the path nodes (level >= 1) read locked, only the leaf needs to be locked while the caller processes it. Therefore make it return a path with all nodes unlocked, except for the leaf. This change is motivated by the observation that during a file fsync we repeatdly call btrfs_search_forward() and process the returned leaf while upper nodes of the returned path (level >= 1) are read locked, which unnecessarily blocks other tasks that want to write to the same fs/subvol btree. Therefore instead of modifying the fsync code to unlock all nodes with level >= 1 immediately after calling btrfs_search_forward(), change btrfs_search_forward() to do it, so that it benefits all callers. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to 'fs/btrfs/ctree.c')
-rw-r--r--fs/btrfs/ctree.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 783ea3bac7dc..39021bf2df9a 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -5144,8 +5144,9 @@ int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
u32 nritems;
int level;
int ret = 1;
+ int keep_locks = path->keep_locks;
- WARN_ON(!path->keep_locks);
+ path->keep_locks = 1;
again:
cur = btrfs_read_lock_root_node(root);
level = btrfs_header_level(cur);
@@ -5209,7 +5210,6 @@ find_next_key:
path->slots[level] = slot;
if (level == path->lowest_level) {
ret = 0;
- unlock_up(path, level, 1, 0, NULL);
goto out;
}
btrfs_set_path_blocking(path);
@@ -5224,9 +5224,12 @@ find_next_key:
btrfs_clear_path_blocking(path, NULL, 0);
}
out:
- if (ret == 0)
+ path->keep_locks = keep_locks;
+ if (ret == 0) {
+ btrfs_unlock_up_safe(path, path->lowest_level + 1);
+ btrfs_set_path_blocking(path);
memcpy(min_key, &found_key, sizeof(found_key));
- btrfs_set_path_blocking(path);
+ }
return ret;
}