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authorJosef Bacik <josef@toxicpanda.com>2018-11-21 14:03:11 -0500
committerDavid Sterba <dsterba@suse.com>2019-02-25 14:13:35 +0100
commit5df1136363cabc4d3f92fc91e3f92bd6a5eebd27 (patch)
tree8d58ce9b0e740b3695f20b0a217ebf935f6d97ee
parentf91587e4151e84f798f37839dddd3e4152fb4c76 (diff)
btrfs: loop in inode_rsv_refill
With severe fragmentation we can end up with our inode rsv size being huge during writeout, which would cause us to need to make very large metadata reservations. However we may not actually need that much once writeout is complete, because of the over-reservation for the worst case. So instead try to make our reservation, and if we couldn't make it re-calculate our new reservation size and try again. If our reservation size doesn't change between tries then we know we are actually out of space and can error. Flushing that could have been running in parallel did not make any space. Signed-off-by: Josef Bacik <josef@toxicpanda.com> [ rename to calc_refill_bytes, update comment and changelog ] Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r--fs/btrfs/extent-tree.c63
1 files changed, 47 insertions, 16 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 566d170d0a0b..cb97ada7f410 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5806,6 +5806,21 @@ int btrfs_block_rsv_refill(struct btrfs_root *root,
return ret;
}
+static void calc_refill_bytes(struct btrfs_block_rsv *block_rsv,
+ u64 *metadata_bytes, u64 *qgroup_bytes)
+{
+ *metadata_bytes = 0;
+ *qgroup_bytes = 0;
+
+ spin_lock(&block_rsv->lock);
+ if (block_rsv->reserved < block_rsv->size)
+ *metadata_bytes = block_rsv->size - block_rsv->reserved;
+ if (block_rsv->qgroup_rsv_reserved < block_rsv->qgroup_rsv_size)
+ *qgroup_bytes = block_rsv->qgroup_rsv_size -
+ block_rsv->qgroup_rsv_reserved;
+ spin_unlock(&block_rsv->lock);
+}
+
/**
* btrfs_inode_rsv_refill - refill the inode block rsv.
* @inode - the inode we are refilling.
@@ -5821,25 +5836,42 @@ static int btrfs_inode_rsv_refill(struct btrfs_inode *inode,
{
struct btrfs_root *root = inode->root;
struct btrfs_block_rsv *block_rsv = &inode->block_rsv;
- u64 num_bytes = 0;
- u64 qgroup_num_bytes = 0;
+ u64 num_bytes, last = 0;
+ u64 qgroup_num_bytes;
int ret = -ENOSPC;
- spin_lock(&block_rsv->lock);
- if (block_rsv->reserved < block_rsv->size)
- num_bytes = block_rsv->size - block_rsv->reserved;
- if (block_rsv->qgroup_rsv_reserved < block_rsv->qgroup_rsv_size)
- qgroup_num_bytes = block_rsv->qgroup_rsv_size -
- block_rsv->qgroup_rsv_reserved;
- spin_unlock(&block_rsv->lock);
-
+ calc_refill_bytes(block_rsv, &num_bytes, &qgroup_num_bytes);
if (num_bytes == 0)
return 0;
- ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_num_bytes, true);
- if (ret)
- return ret;
- ret = reserve_metadata_bytes(root, block_rsv, num_bytes, flush);
+ do {
+ ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_num_bytes,
+ true);
+ if (ret)
+ return ret;
+ ret = reserve_metadata_bytes(root, block_rsv, num_bytes, flush);
+ if (ret) {
+ btrfs_qgroup_free_meta_prealloc(root, qgroup_num_bytes);
+ last = num_bytes;
+ /*
+ * If we are fragmented we can end up with a lot of
+ * outstanding extents which will make our size be much
+ * larger than our reserved amount.
+ *
+ * If the reservation happens here, it might be very
+ * big though not needed in the end, if the delalloc
+ * flushing happens.
+ *
+ * If this is the case try and do the reserve again.
+ */
+ if (flush == BTRFS_RESERVE_FLUSH_ALL)
+ calc_refill_bytes(block_rsv, &num_bytes,
+ &qgroup_num_bytes);
+ if (num_bytes == 0)
+ return 0;
+ }
+ } while (ret && last != num_bytes);
+
if (!ret) {
block_rsv_add_bytes(block_rsv, num_bytes, false);
trace_btrfs_space_reservation(root->fs_info, "delalloc",
@@ -5849,8 +5881,7 @@ static int btrfs_inode_rsv_refill(struct btrfs_inode *inode,
spin_lock(&block_rsv->lock);
block_rsv->qgroup_rsv_reserved += qgroup_num_bytes;
spin_unlock(&block_rsv->lock);
- } else
- btrfs_qgroup_free_meta_prealloc(root, qgroup_num_bytes);
+ }
return ret;
}