| Message ID | 20180928111821.24376-17-josef@toxicpanda.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | My current patch queue | expand |
On Fri, Sep 28, 2018 at 07:17:55AM -0400, Josef Bacik wrote: > 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. 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 out. > > Signed-off-by: Josef Bacik <josef@toxicpanda.com> > --- > fs/btrfs/extent-tree.c | 26 ++++++++++++++++++++++++-- > 1 file changed, 24 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 7a53f6a29ebc..461b8076928b 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -5781,10 +5781,11 @@ 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 num_bytes = 0, last = 0; > u64 qgroup_num_bytes = 0; > int ret = -ENOSPC; > > +again: Could this be restructured so there's no new 'goto again;' pattern added?
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 7a53f6a29ebc..461b8076928b 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5781,10 +5781,11 @@ 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 num_bytes = 0, last = 0; u64 qgroup_num_bytes = 0; int ret = -ENOSPC; +again: spin_lock(&block_rsv->lock); if (block_rsv->reserved < block_rsv->size) num_bytes = block_rsv->size - block_rsv->reserved; @@ -5796,6 +5797,13 @@ static int btrfs_inode_rsv_refill(struct btrfs_inode *inode, if (num_bytes == 0) return 0; + /* + * If our reservation size hasn't changed since the last time we tried + * to make an allocation we can just bail. + */ + if (last && last == num_bytes) + return -ENOSPC; + ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_num_bytes, true); if (ret) return ret; @@ -5809,8 +5817,22 @@ 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 + } else { btrfs_qgroup_free_meta_prealloc(root, qgroup_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 we happen to try to do a reservation + * here that may result in us trying to do a pretty hefty + * reservation, which we may not need once delalloc flushing + * happens. If this is the case try and do the reserve again. + */ + if (flush == BTRFS_RESERVE_FLUSH_ALL) { + last = num_bytes; + goto again; + } + } return ret; }
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. 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 out. Signed-off-by: Josef Bacik <josef@toxicpanda.com> --- fs/btrfs/extent-tree.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-)