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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
parentea9947b4395fa34666086b2fa6f686e94903e047 (diff)
downloadlinux-linaro-stable-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')
-rw-r--r--fs/btrfs/ctree.c26
-rw-r--r--fs/btrfs/disk-io.c18
-rw-r--r--fs/btrfs/disk-io.h3
-rw-r--r--fs/btrfs/extent-tree.c2
-rw-r--r--fs/btrfs/tree-log.c2
5 files changed, 34 insertions, 17 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 086303b9be64..4106264fbc65 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -725,7 +725,7 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans,
cur = btrfs_find_tree_block(root, blocknr, blocksize);
if (cur)
- uptodate = btrfs_buffer_uptodate(cur, gen);
+ uptodate = btrfs_buffer_uptodate(cur, gen, 0);
else
uptodate = 0;
if (!cur || !uptodate) {
@@ -1360,7 +1360,12 @@ static noinline int reada_for_balance(struct btrfs_root *root,
block1 = btrfs_node_blockptr(parent, slot - 1);
gen = btrfs_node_ptr_generation(parent, slot - 1);
eb = btrfs_find_tree_block(root, block1, blocksize);
- if (eb && btrfs_buffer_uptodate(eb, gen))
+ /*
+ * if we get -eagain from btrfs_buffer_uptodate, we
+ * don't want to return eagain here. That will loop
+ * forever
+ */
+ if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
block1 = 0;
free_extent_buffer(eb);
}
@@ -1368,7 +1373,7 @@ static noinline int reada_for_balance(struct btrfs_root *root,
block2 = btrfs_node_blockptr(parent, slot + 1);
gen = btrfs_node_ptr_generation(parent, slot + 1);
eb = btrfs_find_tree_block(root, block2, blocksize);
- if (eb && btrfs_buffer_uptodate(eb, gen))
+ if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
block2 = 0;
free_extent_buffer(eb);
}
@@ -1506,8 +1511,9 @@ read_block_for_search(struct btrfs_trans_handle *trans,
tmp = btrfs_find_tree_block(root, blocknr, blocksize);
if (tmp) {
- if (btrfs_buffer_uptodate(tmp, 0)) {
- if (btrfs_buffer_uptodate(tmp, gen)) {
+ /* first we do an atomic uptodate check */
+ if (btrfs_buffer_uptodate(tmp, 0, 1) > 0) {
+ if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
/*
* we found an up to date block without
* sleeping, return
@@ -1525,8 +1531,9 @@ read_block_for_search(struct btrfs_trans_handle *trans,
free_extent_buffer(tmp);
btrfs_set_path_blocking(p);
+ /* now we're allowed to do a blocking uptodate check */
tmp = read_tree_block(root, blocknr, blocksize, gen);
- if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
+ if (tmp && btrfs_buffer_uptodate(tmp, gen, 0) > 0) {
*eb_ret = tmp;
return 0;
}
@@ -1561,7 +1568,7 @@ read_block_for_search(struct btrfs_trans_handle *trans,
* and give up so that our caller doesn't loop forever
* on our EAGAINs.
*/
- if (!btrfs_buffer_uptodate(tmp, 0))
+ if (!btrfs_buffer_uptodate(tmp, 0, 0))
ret = -EIO;
free_extent_buffer(tmp);
}
@@ -4045,7 +4052,7 @@ again:
tmp = btrfs_find_tree_block(root, blockptr,
btrfs_level_size(root, level - 1));
- if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
+ if (tmp && btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
free_extent_buffer(tmp);
break;
}
@@ -4168,7 +4175,8 @@ next:
struct extent_buffer *cur;
cur = btrfs_find_tree_block(root, blockptr,
btrfs_level_size(root, level - 1));
- if (!cur || !btrfs_buffer_uptodate(cur, gen)) {
+ if (!cur ||
+ btrfs_buffer_uptodate(cur, gen, 1) <= 0) {
slot++;
if (cur)
free_extent_buffer(cur);
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;
}
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index a7ace1a2dd12..ab1830aaf0ed 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -66,7 +66,8 @@ void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr);
void __btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr);
void btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root);
void btrfs_mark_buffer_dirty(struct extent_buffer *buf);
-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 btrfs_set_buffer_uptodate(struct extent_buffer *buf);
int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid);
u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 6fc2e6f5aab8..49fd7b66d57b 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6568,7 +6568,7 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
goto skip;
}
- if (!btrfs_buffer_uptodate(next, generation)) {
+ if (!btrfs_buffer_uptodate(next, generation, 0)) {
btrfs_tree_unlock(next);
free_extent_buffer(next);
next = NULL;
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index d017283ae6f5..eb1ae908582c 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -279,7 +279,7 @@ static int process_one_buffer(struct btrfs_root *log,
log->fs_info->extent_root,
eb->start, eb->len);
- if (btrfs_buffer_uptodate(eb, gen)) {
+ if (btrfs_buffer_uptodate(eb, gen, 0)) {
if (wc->write)
btrfs_write_tree_block(eb);
if (wc->wait)