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authorJosef Bacik <josef@redhat.com>2010-03-19 14:38:13 +0000
committerChris Mason <chris.mason@oracle.com>2010-04-05 16:04:50 -0400
commitab6e24103cbd215e922938a4f58c75194761a60e (patch)
treed54479feddd7fe625888dd62084621d4d0871c4b
parent109f6aef5fc436f355ad027f4d97bd696df2049a (diff)
downloadop-kernel-dev-ab6e24103cbd215e922938a4f58c75194761a60e.zip
op-kernel-dev-ab6e24103cbd215e922938a4f58c75194761a60e.tar.gz
Btrfs: fix data enospc check overflow
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> Signed-off-by: Chris Mason <chris.mason@oracle.com>
-rw-r--r--fs/btrfs/extent-tree.c20
1 files changed, 15 insertions, 5 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 101041d..786899d 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.
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