[PATCH] Fix inode list allocation size in writeback.

[PATCH] Fix inode list allocation size in writeback.

[David Chinner]

We only need to allocate space for the number of inodes in
the cluster when writing back inodes, not every byte in the
inode cluster. This reduces the amount of memory needing to
be allocated to 256 bytes instead of 64k.

Somebody pass me the brown paper bag, please.

Signed-off-by: Dave Chinner <dgc@sgi.com>
---
 fs/xfs/xfs_inode.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Index: 2.6.x-xfs-new/fs/xfs/xfs_inode.c
===================================================================
--- 2.6.x-xfs-new.orig/fs/xfs/xfs_inode.c	2008-05-16 19:43:55.000000000 +1000
+++ 2.6.x-xfs-new/fs/xfs/xfs_inode.c	2008-05-16 19:47:47.778141722 +1000
@@ -2913,6 +2913,7 @@ xfs_iflush_cluster(
 	xfs_mount_t		*mp = ip->i_mount;
 	xfs_perag_t		*pag = xfs_get_perag(mp, ip->i_ino);
 	unsigned long		first_index, mask;
+	unsigned long		inodes_per_cluster;
 	int			ilist_size;
 	xfs_inode_t		**ilist;
 	xfs_inode_t		*iq;
@@ -2924,7 +2925,8 @@ xfs_iflush_cluster(
 	ASSERT(pag->pagi_inodeok);
 	ASSERT(pag->pag_ici_init);
 
-	ilist_size = XFS_INODE_CLUSTER_SIZE(mp) * sizeof(xfs_inode_t *);
+	inodes_per_cluster = XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_inodelog;
+	ilist_size = inodes_per_cluster * sizeof(xfs_inode_t *);
 	ilist = kmem_alloc(ilist_size, KM_MAYFAIL|KM_NOFS);
 	if (!ilist)
 		return 0;
@@ -2934,8 +2936,7 @@ xfs_iflush_cluster(
 	read_lock(&pag->pag_ici_lock);
 	/* really need a gang lookup range call here */
 	nr_found = radix_tree_gang_lookup(&pag->pag_ici_root, (void**)ilist,
-					first_index,
-					XFS_INODE_CLUSTER_SIZE(mp));
+					first_index, inodes_per_cluster);
 	if (nr_found == 0)
 		goto out_free;
 

Re: [PATCH] Fix inode list allocation size in writeback.

[Christoph Hellwig]

On Fri, May 16, 2008 at 08:06:57PM +1000, David Chinner wrote:
> We only need to allocate space for the number of inodes in
> the cluster when writing back inodes, not every byte in the
> inode cluster. This reduces the amount of memory needing to
> be allocated to 256 bytes instead of 64k.
> 
> Somebody pass me the brown paper bag, please.

Looks good, and I'll happily pass on my brown paper bag :)