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author | Chris Mason <chris.mason@oracle.com> | 2012-05-06 07:23:47 -0400 |
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committer | Chris Mason <chris.mason@oracle.com> | 2012-05-06 07:23:47 -0400 |
commit | b9fab919b748c7b39c19ff236ed6c5682c266dde (patch) | |
tree | 49e5a6f8041a7f0a9be0c1a39cd9088e3faa1df2 /fs/btrfs/disk-io.c | |
parent | ea9947b4395fa34666086b2fa6f686e94903e047 (diff) | |
download | linux-stable-b9fab919b748c7b39c19ff236ed6c5682c266dde.tar.gz linux-stable-b9fab919b748c7b39c19ff236ed6c5682c266dde.tar.bz2 linux-stable-b9fab919b748c7b39c19ff236ed6c5682c266dde.zip |
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.c | 18 |
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; } |