[XFS] Return case-insensitive match for dentry cache
This implements the code to store the actual filename found during a
lookup in the dentry cache and to avoid multiple entries in the dcache
pointing to the same inode.
To avoid polluting the dcache, we implement a new directory inode
operations for lookup. xfs_vn_ci_lookup() stores the correct case name in
the dcache.
The "actual name" is only allocated and returned for a case- insensitive
match and not an actual match.
Another unusual interaction with the dcache is not storing negative
dentries like other filesystems doing a d_add(dentry, NULL) when an ENOENT
is returned. During the VFS lookup, if a dentry returned has no inode,
dput is called and ENOENT is returned. By not doing a d_add, this actually
removes it completely from the dcache to be reused. create/rename have to
be modified to support unhashed dentries being passed in.
SGI-PV: 981521
SGI-Modid: xfs-linux-melb:xfs-kern:31208a
Signed-off-by: Barry Naujok <bnaujok@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 9b8b87f..b6a065e 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -1610,12 +1610,18 @@
return VN_INACTIVE_CACHE;
}
-
+/*
+ * Lookups up an inode from "name". If ci_name is not NULL, then a CI match
+ * is allowed, otherwise it has to be an exact match. If a CI match is found,
+ * ci_name->name will point to a the actual name (caller must free) or
+ * will be set to NULL if an exact match is found.
+ */
int
xfs_lookup(
xfs_inode_t *dp,
struct xfs_name *name,
- xfs_inode_t **ipp)
+ xfs_inode_t **ipp,
+ struct xfs_name *ci_name)
{
xfs_ino_t inum;
int error;
@@ -1627,7 +1633,7 @@
return XFS_ERROR(EIO);
lock_mode = xfs_ilock_map_shared(dp);
- error = xfs_dir_lookup(NULL, dp, name, &inum);
+ error = xfs_dir_lookup(NULL, dp, name, &inum, ci_name);
xfs_iunlock_map_shared(dp, lock_mode);
if (error)
@@ -1635,12 +1641,15 @@
error = xfs_iget(dp->i_mount, NULL, inum, 0, 0, ipp, 0);
if (error)
- goto out;
+ goto out_free_name;
xfs_itrace_ref(*ipp);
return 0;
- out:
+out_free_name:
+ if (ci_name)
+ kmem_free(ci_name->name);
+out:
*ipp = NULL;
return error;
}