From: Josef Bacik <jba...@fb.com>
Since we're allocating under atomic we could every easily enomem, so if
that's the case and we can block then loop around and try to allocate
the prealloc not under a lock.
We also saw this happen during try_to_release_page in production, in
which case it's completely valid to return ENOMEM so we can tell
try_to_release_page that we can't release this page.
Signed-off-by: Josef Bacik <jba...@fb.com>
---
v1->v2:
- this time with my local changes committed!
fs/btrfs/extent_io.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index dd941885b9c3..fb0c1636c1c4 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -590,8 +590,9 @@ static int __clear_extent_bit(struct extent_io_tree *tree,
u64 start, u64 end,
struct extent_state *prealloc = NULL;
struct rb_node *node;
u64 last_end;
- int err;
+ int err = 0;
int clear = 0;
+ bool need_prealloc = false;
btrfs_debug_check_extent_io_range(tree, start, end);
@@ -614,6 +615,9 @@ static int __clear_extent_bit(struct extent_io_tree *tree,
u64 start, u64 end,
* If we end up needing a new extent state we allocate it later.
*/
prealloc = alloc_extent_state(mask);
+ if (!prealloc && need_prealloc)
+ return -ENOMEM;
+ need_prealloc = false;
}
spin_lock(&tree->lock);
@@ -673,7 +677,15 @@ static int __clear_extent_bit(struct extent_io_tree *tree,
u64 start, u64 end,
if (state->start < start) {
prealloc = alloc_extent_state_atomic(prealloc);
- BUG_ON(!prealloc);
+ if (!prealloc) {
+ if (gfpflags_allow_blocking(mask)) {
+ need_prealloc = true;
+ spin_unlock(&tree->lock);
+ goto again;
+ }
+ err = -ENOMEM;
+ goto out;
+ }
err = split_state(tree, state, prealloc, start);
if (err)
extent_io_tree_panic(tree, err);
@@ -696,7 +708,15 @@ static int __clear_extent_bit(struct extent_io_tree *tree,
u64 start, u64 end,
*/
if (state->start <= end && state->end > end) {
prealloc = alloc_extent_state_atomic(prealloc);
- BUG_ON(!prealloc);
+ if (!prealloc) {
+ if (gfpflags_allow_blocking(mask)) {
+ need_prealloc = true;
+ spin_unlock(&tree->lock);
+ goto again;
+ }
+ err = -ENOMEM;
+ goto out;
+ }
err = split_state(tree, state, prealloc, end + 1);
if (err)
extent_io_tree_panic(tree, err);
@@ -731,7 +751,7 @@ static int __clear_extent_bit(struct extent_io_tree *tree,
u64 start, u64 end,
if (prealloc)
free_extent_state(prealloc);
- return 0;
+ return err;
}
--
2.7.5
--
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