Because we account for reserved space we get from the allocator before we
actually account for allocating delalloc space, we can have a small window where
the amount of "used" space in a space_info is more than the total
amount of
space in the space_info. This will cause a overflow in our check, so it will
seem like we have _tons_ of free space, and we''ll allow reservations to
occur
that will end up larger than the amount of space we have. I''ve seen
users
report ENOSPC panic''s in cow_file_range a few times recently, so I
tried to
reproduce this problem and found I could reproduce it if I ran one of my tests
in a loop for like 20 minutes. With this patch my test ran all night without
issues. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
---
fs/btrfs/extent-tree.c | 20 +++++++++++++++-----
1 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 7bb97de..1860969 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3234,7 +3234,8 @@ int btrfs_check_data_free_space(struct btrfs_root *root,
struct inode *inode,
u64 bytes)
{
struct btrfs_space_info *data_sinfo;
- int ret = 0, committed = 0;
+ u64 used;
+ int ret = 0, committed = 0, flushed = 0;
/* make sure bytes are sectorsize aligned */
bytes = (bytes + root->sectorsize - 1) & ~((u64)root->sectorsize -
1);
@@ -3246,12 +3247,21 @@ int btrfs_check_data_free_space(struct btrfs_root *root,
struct inode *inode,
again:
/* make sure we have enough space to handle the data first */
spin_lock(&data_sinfo->lock);
- if (data_sinfo->total_bytes - data_sinfo->bytes_used -
- data_sinfo->bytes_delalloc - data_sinfo->bytes_reserved -
- data_sinfo->bytes_pinned - data_sinfo->bytes_readonly -
- data_sinfo->bytes_may_use - data_sinfo->bytes_super < bytes) {
+ used = data_sinfo->bytes_used + data_sinfo->bytes_delalloc +
+ data_sinfo->bytes_reserved + data_sinfo->bytes_pinned +
+ data_sinfo->bytes_readonly + data_sinfo->bytes_may_use +
+ data_sinfo->bytes_super;
+
+ if (used + bytes > data_sinfo->total_bytes) {
struct btrfs_trans_handle *trans;
+ if (!flushed) {
+ spin_unlock(&data_sinfo->lock);
+ flush_delalloc(root, data_sinfo);
+ flushed = 1;
+ goto again;
+ }
+
/*
* if we don''t have enough free bytes in this space then we need
* to alloc a new chunk.
--
1.6.6
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