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-rw-r--r--fs/btrfs/inode.c57
1 files changed, 30 insertions, 27 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 97b601bec326..bb74a4181075 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1542,30 +1542,17 @@ static void btrfs_split_extent_hook(struct inode *inode,
u64 new_size;
/*
- * We need the largest size of the remaining extent to see if we
- * need to add a new outstanding extent. Think of the following
- * case
- *
- * [MEAX_EXTENT_SIZEx2 - 4k][4k]
- *
- * The new_size would just be 4k and we'd think we had enough
- * outstanding extents for this if we only took one side of the
- * split, same goes for the other direction. We need to see if
- * the larger size still is the same amount of extents as the
- * original size, because if it is we need to add a new
- * outstanding extent. But if we split up and the larger size
- * is less than the original then we are good to go since we've
- * already accounted for the extra extent in our original
- * accounting.
+ * See the explanation in btrfs_merge_extent_hook, the same
+ * applies here, just in reverse.
*/
new_size = orig->end - split + 1;
- if ((split - orig->start) > new_size)
- new_size = split - orig->start;
-
- num_extents = div64_u64(size + BTRFS_MAX_EXTENT_SIZE - 1,
+ num_extents = div64_u64(new_size + BTRFS_MAX_EXTENT_SIZE - 1,
BTRFS_MAX_EXTENT_SIZE);
- if (div64_u64(new_size + BTRFS_MAX_EXTENT_SIZE - 1,
- BTRFS_MAX_EXTENT_SIZE) < num_extents)
+ new_size = split - orig->start;
+ num_extents += div64_u64(new_size + BTRFS_MAX_EXTENT_SIZE - 1,
+ BTRFS_MAX_EXTENT_SIZE);
+ if (div64_u64(size + BTRFS_MAX_EXTENT_SIZE - 1,
+ BTRFS_MAX_EXTENT_SIZE) >= num_extents)
return;
}
@@ -1591,9 +1578,6 @@ static void btrfs_merge_extent_hook(struct inode *inode,
if (!(other->state & EXTENT_DELALLOC))
return;
- old_size = other->end - other->start + 1;
- if (old_size < (new->end - new->start + 1))
- old_size = (new->end - new->start + 1);
if (new->start > other->start)
new_size = new->end - other->start + 1;
else
@@ -1608,13 +1592,32 @@ static void btrfs_merge_extent_hook(struct inode *inode,
}
/*
- * If we grew by another max_extent, just return, we want to keep that
- * reserved amount.
+ * We have to add up either side to figure out how many extents were
+ * accounted for before we merged into one big extent. If the number of
+ * extents we accounted for is <= the amount we need for the new range
+ * then we can return, otherwise drop. Think of it like this
+ *
+ * [ 4k][MAX_SIZE]
+ *
+ * So we've grown the extent by a MAX_SIZE extent, this would mean we
+ * need 2 outstanding extents, on one side we have 1 and the other side
+ * we have 1 so they are == and we can return. But in this case
+ *
+ * [MAX_SIZE+4k][MAX_SIZE+4k]
+ *
+ * Each range on their own accounts for 2 extents, but merged together
+ * they are only 3 extents worth of accounting, so we need to drop in
+ * this case.
*/
+ old_size = other->end - other->start + 1;
num_extents = div64_u64(old_size + BTRFS_MAX_EXTENT_SIZE - 1,
BTRFS_MAX_EXTENT_SIZE);
+ old_size = new->end - new->start + 1;
+ num_extents += div64_u64(old_size + BTRFS_MAX_EXTENT_SIZE - 1,
+ BTRFS_MAX_EXTENT_SIZE);
+
if (div64_u64(new_size + BTRFS_MAX_EXTENT_SIZE - 1,
- BTRFS_MAX_EXTENT_SIZE) > num_extents)
+ BTRFS_MAX_EXTENT_SIZE) >= num_extents)
return;
spin_lock(&BTRFS_I(inode)->lock);