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>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 086303b9..4106264 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -725,7 +725,7 @@
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 @@
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 @@
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 @@
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 @@
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 @@
* 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 @@
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 @@
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);