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authorChris Mason <chris.mason@oracle.com>2012-05-06 07:23:47 -0400
committerChris Mason <chris.mason@oracle.com>2012-05-06 07:23:47 -0400
commitb9fab919b748c7b39c19ff236ed6c5682c266dde (patch)
tree49e5a6f8041a7f0a9be0c1a39cd9088e3faa1df2 /fs/btrfs/disk-io.c
parentea9947b4395fa34666086b2fa6f686e94903e047 (diff)
downloadlinux-stericsson-b9fab919b748c7b39c19ff236ed6c5682c266dde.tar.gz
Btrfs: avoid sleeping in verify_parent_transid while atomic
verify_parent_transid needs to lock the extent range to make sure no IO is underway, and so it can safely clear the uptodate bits if our checks fail. But, a few callers are using it with spinlocks held. Most of the time, the generation numbers are going to match, and we don't want to switch to a blocking lock just for the error case. This adds an atomic flag to verify_parent_transid, and changes it to return EAGAIN if it needs to block to properly verifiy things. Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/disk-io.c')
-rw-r--r--fs/btrfs/disk-io.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index d0c969beaad4..a7ffc88a7dbe 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -323,7 +323,8 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
* in the wrong place.
*/
static int verify_parent_transid(struct extent_io_tree *io_tree,
- struct extent_buffer *eb, u64 parent_transid)
+ struct extent_buffer *eb, u64 parent_transid,
+ int atomic)
{
struct extent_state *cached_state = NULL;
int ret;
@@ -331,6 +332,9 @@ static int verify_parent_transid(struct extent_io_tree *io_tree,
if (!parent_transid || btrfs_header_generation(eb) == parent_transid)
return 0;
+ if (atomic)
+ return -EAGAIN;
+
lock_extent_bits(io_tree, eb->start, eb->start + eb->len - 1,
0, &cached_state);
if (extent_buffer_uptodate(eb) &&
@@ -372,7 +376,8 @@ static int btree_read_extent_buffer_pages(struct btrfs_root *root,
ret = read_extent_buffer_pages(io_tree, eb, start,
WAIT_COMPLETE,
btree_get_extent, mirror_num);
- if (!ret && !verify_parent_transid(io_tree, eb, parent_transid))
+ if (!ret && !verify_parent_transid(io_tree, eb,
+ parent_transid, 0))
break;
/*
@@ -1202,7 +1207,7 @@ static int __must_check find_and_setup_root(struct btrfs_root *tree_root,
root->commit_root = NULL;
root->node = read_tree_block(root, btrfs_root_bytenr(&root->root_item),
blocksize, generation);
- if (!root->node || !btrfs_buffer_uptodate(root->node, generation)) {
+ if (!root->node || !btrfs_buffer_uptodate(root->node, generation, 0)) {
free_extent_buffer(root->node);
root->node = NULL;
return -EIO;
@@ -3143,7 +3148,8 @@ int close_ctree(struct btrfs_root *root)
return 0;
}
-int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid)
+int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid,
+ int atomic)
{
int ret;
struct inode *btree_inode = buf->pages[0]->mapping->host;
@@ -3153,7 +3159,9 @@ int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid)
return ret;
ret = verify_parent_transid(&BTRFS_I(btree_inode)->io_tree, buf,
- parent_transid);
+ parent_transid, atomic);
+ if (ret == -EAGAIN)
+ return ret;
return !ret;
}