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authorChris Mason <chris.mason@oracle.com>2009-05-14 13:24:30 -0400
committerChris Mason <chris.mason@oracle.com>2009-05-14 14:00:32 -0400
commit76a05b35a320e8c968d0fec8f512a1acae227309 (patch)
tree611875a5ea273de7208c84884a0ec59d985eb614 /fs
parent2757495c906113896b378bf084708846273c87b2 (diff)
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Btrfs: Don't loop forever on metadata IO failures
When a btrfs metadata read fails, the first thing we try to do is find a good copy on another mirror of the block. If this fails, read_tree_block() ends up returning a buffer that isn't up to date. The btrfs btree reading code was reworked to drop locks and repeat the search when IO was done, but the changes didn't add a check for failed reads. The end result was looping forever on buffers that were never going to become up to date. Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/ctree.c39
1 files changed, 36 insertions, 3 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index a99f1c2a710..fedf8b9f03a 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1469,6 +1469,7 @@ read_block_for_search(struct btrfs_trans_handle *trans,
u32 blocksize;
struct extent_buffer *b = *eb_ret;
struct extent_buffer *tmp;
+ int ret;
blocknr = btrfs_node_blockptr(b, slot);
gen = btrfs_node_ptr_generation(b, slot);
@@ -1476,6 +1477,10 @@ read_block_for_search(struct btrfs_trans_handle *trans,
tmp = btrfs_find_tree_block(root, blocknr, blocksize);
if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
+ /*
+ * we found an up to date block without sleeping, return
+ * right away
+ */
*eb_ret = tmp;
return 0;
}
@@ -1483,7 +1488,9 @@ read_block_for_search(struct btrfs_trans_handle *trans,
/*
* reduce lock contention at high levels
* of the btree by dropping locks before
- * we read.
+ * we read. Don't release the lock on the current
+ * level because we need to walk this node to figure
+ * out which blocks to read.
*/
btrfs_unlock_up_safe(p, level + 1);
btrfs_set_path_blocking(p);
@@ -1494,10 +1501,21 @@ read_block_for_search(struct btrfs_trans_handle *trans,
reada_for_search(root, p, level, slot, key->objectid);
btrfs_release_path(NULL, p);
+
+ ret = -EAGAIN;
tmp = read_tree_block(root, blocknr, blocksize, gen);
- if (tmp)
+ if (tmp) {
+ /*
+ * If the read above didn't mark this buffer up to date,
+ * it will never end up being up to date. Set ret to EIO now
+ * and give up so that our caller doesn't loop forever
+ * on our EAGAINs.
+ */
+ if (!btrfs_buffer_uptodate(tmp, 0))
+ ret = -EIO;
free_extent_buffer(tmp);
- return -EAGAIN;
+ }
+ return ret;
}
/*
@@ -1696,6 +1714,9 @@ cow_done:
if (ret == -EAGAIN)
goto again;
+ if (ret == -EIO)
+ goto done;
+
if (!p->skip_locking) {
int lret;
@@ -1738,6 +1759,8 @@ done:
*/
if (!p->leave_spinning)
btrfs_set_path_blocking(p);
+ if (ret < 0)
+ btrfs_release_path(root, p);
return ret;
}
@@ -4212,6 +4235,11 @@ again:
if (ret == -EAGAIN)
goto again;
+ if (ret < 0) {
+ btrfs_release_path(root, path);
+ goto done;
+ }
+
if (!path->skip_locking) {
ret = btrfs_try_spin_lock(next);
if (!ret) {
@@ -4246,6 +4274,11 @@ again:
if (ret == -EAGAIN)
goto again;
+ if (ret < 0) {
+ btrfs_release_path(root, path);
+ goto done;
+ }
+
if (!path->skip_locking) {
btrfs_assert_tree_locked(path->nodes[level]);
ret = btrfs_try_spin_lock(next);