Commit 384f3ced authored by Barry Naujok's avatar Barry Naujok Committed by Niv Sardi
Browse files

[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: default avatarBarry Naujok <bnaujok@sgi.com>
Signed-off-by: default avatarChristoph Hellwig <hch@infradead.org>
parent 9403540c

fs/xfs/linux-2.6/xfs_export.c

+1 −1
Original line number Diff line number Diff line
@@ -215,7 +215,7 @@ xfs_fs_get_parent( 
	struct xfs_inode	*cip;

	struct dentry		*parent;



	error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip);

	error = xfs_lookup(XFS_I(child->d_inode), &xfs_name_dotdot, &cip, NULL);

	if (unlikely(error))

		return ERR_PTR(-error);

fs/xfs/linux-2.6/xfs_iops.c

+56 −1
Original line number Diff line number Diff line
@@ -382,7 +382,7 @@ xfs_vn_lookup( 
		return ERR_PTR(-ENAMETOOLONG);



	xfs_dentry_to_name(&name, dentry);

	error = xfs_lookup(XFS_I(dir), &name, &cip);

	error = xfs_lookup(XFS_I(dir), &name, &cip, NULL);

	if (unlikely(error)) {

		if (unlikely(error != ENOENT))

			return ERR_PTR(-error);
@@ -393,6 +393,42 @@ xfs_vn_lookup( 
	return d_splice_alias(cip->i_vnode, dentry);

}



STATIC struct dentry *

xfs_vn_ci_lookup(

	struct inode	*dir,

	struct dentry	*dentry,

	struct nameidata *nd)

{

	struct xfs_inode *ip;

	struct xfs_name	xname;

	struct xfs_name ci_name;

	struct qstr	dname;

	int		error;



	if (dentry->d_name.len >= MAXNAMELEN)

		return ERR_PTR(-ENAMETOOLONG);



	xfs_dentry_to_name(&xname, dentry);

	error = xfs_lookup(XFS_I(dir), &xname, &ip, &ci_name);

	if (unlikely(error)) {

		if (unlikely(error != ENOENT))

			return ERR_PTR(-error);

		d_add(dentry, NULL);

		return NULL;

	}



	/* if exact match, just splice and exit */

	if (!ci_name.name)

		return d_splice_alias(ip->i_vnode, dentry);



	/* else case-insensitive match... */

	dname.name = ci_name.name;

	dname.len = ci_name.len;

	dentry = d_add_ci(ip->i_vnode, dentry, &dname);

	kmem_free(ci_name.name);

	return dentry;

}



STATIC int

xfs_vn_link(

	struct dentry	*old_dentry,
@@ -892,6 +928,25 @@ const struct inode_operations xfs_dir_inode_operations = { 
	.removexattr		= xfs_vn_removexattr,

};



const struct inode_operations xfs_dir_ci_inode_operations = {

	.create			= xfs_vn_create,

	.lookup			= xfs_vn_ci_lookup,

	.link			= xfs_vn_link,

	.unlink			= xfs_vn_unlink,

	.symlink		= xfs_vn_symlink,

	.mkdir			= xfs_vn_mkdir,

	.rmdir			= xfs_vn_rmdir,

	.mknod			= xfs_vn_mknod,

	.rename			= xfs_vn_rename,

	.permission		= xfs_vn_permission,

	.getattr		= xfs_vn_getattr,

	.setattr		= xfs_vn_setattr,

	.setxattr		= xfs_vn_setxattr,

	.getxattr		= xfs_vn_getxattr,

	.listxattr		= xfs_vn_listxattr,

	.removexattr		= xfs_vn_removexattr,

};



const struct inode_operations xfs_symlink_inode_operations = {

	.readlink		= generic_readlink,

	.follow_link		= xfs_vn_follow_link,

fs/xfs/linux-2.6/xfs_iops.h

+1 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 


extern const struct inode_operations xfs_inode_operations;

extern const struct inode_operations xfs_dir_inode_operations;

extern const struct inode_operations xfs_dir_ci_inode_operations;

extern const struct inode_operations xfs_symlink_inode_operations;



extern const struct file_operations xfs_file_operations;

fs/xfs/xfs_da_btree.h

+1 −0
Original line number Diff line number Diff line
@@ -143,6 +143,7 @@ typedef struct xfs_da_args { 
#define XFS_DA_OP_RENAME	0x0002	/* this is an atomic rename op */

#define XFS_DA_OP_ADDNAME	0x0004	/* this is an add operation */

#define XFS_DA_OP_OKNOENT	0x0008	/* lookup/add op, ENOENT ok, else die */

#define XFS_DA_OP_CILOOKUP	0x0010	/* lookup to return CI name if found */



/*

 * Structure to describe buffer(s) for a block.

fs/xfs/xfs_dir2.c

+38 −2
Original line number Diff line number Diff line
@@ -192,15 +192,44 @@ xfs_dir_createname( 
	return rval;

}



/*

 * If doing a CI lookup and case-insensitive match, dup actual name into

 * args.value. Return EEXIST for success (ie. name found) or an error.

 */

int

xfs_dir_cilookup_result(

	struct xfs_da_args *args,

	const char	*name,

	int		len)

{

	if (args->cmpresult == XFS_CMP_DIFFERENT)

		return ENOENT;

	if (args->cmpresult != XFS_CMP_CASE ||

					!(args->op_flags & XFS_DA_OP_CILOOKUP))

		return EEXIST;



	args->value = kmem_alloc(len, KM_MAYFAIL);

	if (!args->value)

		return ENOMEM;



	memcpy(args->value, name, len);

	args->valuelen = len;

	return EEXIST;

}



/*

 * Lookup a name in a directory, give back the inode number.

 * If ci_name is not NULL, returns the actual name in ci_name if it differs

 * to name, or ci_name->name is set to NULL for an exact match.

 */



int

xfs_dir_lookup(

	xfs_trans_t	*tp,

	xfs_inode_t	*dp,

	struct xfs_name	*name,

	xfs_ino_t	*inum)		/* out: inode number */

	xfs_ino_t	*inum,		/* out: inode number */

	struct xfs_name *ci_name)	/* out: actual name if CI match */

{

	xfs_da_args_t	args;

	int		rval;
@@ -217,6 +246,8 @@ xfs_dir_lookup( 
	args.whichfork = XFS_DATA_FORK;

	args.trans = tp;

	args.op_flags = XFS_DA_OP_OKNOENT;

	if (ci_name)

		args.op_flags |= XFS_DA_OP_CILOOKUP;

	args.cmpresult = XFS_CMP_DIFFERENT;



	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
@@ -233,8 +264,13 @@ xfs_dir_lookup( 
		rval = xfs_dir2_node_lookup(&args);

	if (rval == EEXIST)

		rval = 0;

	if (rval == 0)

	if (!rval) {

		*inum = args.inumber;

		if (ci_name) {

			ci_name->name = args.value;

			ci_name->len = args.valuelen;

		}

	}

	return rval;

}

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