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Commit 1b524672 authored by OGAWA Hirofumi's avatar OGAWA Hirofumi Committed by Linus Torvalds
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fat: Fix/Cleanup dcache handling for vfat 



- Add comments for handling dcache of vfat.

- Separate case-sensitive case and case-insensitive to
  vfat_revalidate() and vfat_ci_revalidate().

  vfat_revalidate() doesn't need to drop case-insensitive negative
  dentry on creation path.

- Current code is missing to set ->d_revalidate to the negative dentry
  created by unlink/etc..

  This sets ->d_revalidate always, and returns 1 for positive
  dentry. Now, we don't need to change ->d_op dynamically anymore,
  so this just uses sb->s_root->d_op to set ->d_op.

- d_find_alias() may return DCACHE_DISCONNECTED dentry. It's not
  the interesting dentry there. This checks it.

- Add missing LOOKUP_PARENT check. We don't need to drop the valid
  negative dentry for (LOOKUP_CREATE | LOOKUP_PARENT) lookup.

- For consistent filename on creation path, this drops negative dentry
  if we can't see intent.

Signed-off-by: default avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 068f5ae0

fs/fat/namei_vfat.c

+80 −44
Original line number Diff line number Diff line
@@ -24,27 +24,67 @@ 
#include <linux/namei.h>

#include "fat.h"



static int vfat_revalidate(struct dentry *dentry, struct nameidata *nd)

{

	int ret = 1;



	if (!dentry->d_inode &&

	    nd && !(nd->flags & LOOKUP_CONTINUE) && (nd->flags & LOOKUP_CREATE))

/*

		 * negative dentry is dropped, in order to make sure

		 * to use the name which a user desires if this is

		 * create path.

 * If new entry was created in the parent, it could create the 8.3

 * alias (the shortname of logname).  So, the parent may have the

 * negative-dentry which matches the created 8.3 alias.

 *

 * If it happened, the negative dentry isn't actually negative

 * anymore.  So, drop it.

 */

		ret = 0;

	else {

static int vfat_revalidate_shortname(struct dentry *dentry)

{

	int ret = 1;

	spin_lock(&dentry->d_lock);

	if (dentry->d_time != dentry->d_parent->d_inode->i_version)

		ret = 0;

	spin_unlock(&dentry->d_lock);

	}

	return ret;

}



static int vfat_revalidate(struct dentry *dentry, struct nameidata *nd)

{

	/* This is not negative dentry. Always valid. */

	if (dentry->d_inode)

		return 1;

	return vfat_revalidate_shortname(dentry);

}



static int vfat_revalidate_ci(struct dentry *dentry, struct nameidata *nd)

{

	/*

	 * This is not negative dentry. Always valid.

	 *

	 * Note, rename() to existing directory entry will have ->d_inode,

	 * and will use existing name which isn't specified name by user.

	 *

	 * We may be able to drop this positive dentry here. But dropping

	 * positive dentry isn't good idea. So it's unsupported like

	 * rename("filename", "FILENAME") for now.

	 */

	if (dentry->d_inode)

		return 1;



	/*

	 * This may be nfsd (or something), anyway, we can't see the

	 * intent of this. So, since this can be for creation, drop it.

	 */

	if (!nd)

		return 0;



	/*

	 * Drop the negative dentry, in order to make sure to use the

	 * case sensitive name which is specified by user if this is

	 * for creation.

	 */

	if (!(nd->flags & (LOOKUP_CONTINUE | LOOKUP_PARENT))) {

		if (nd->flags & LOOKUP_CREATE)

			return 0;

	}



	return vfat_revalidate_shortname(dentry);

}



/* returns the length of a struct qstr, ignoring trailing dots */

static unsigned int vfat_striptail_len(struct qstr *qstr)

{
@@ -126,25 +166,16 @@ static int vfat_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b) 
	return 1;

}



static struct dentry_operations vfat_dentry_ops[4] = {

	{

		.d_hash		= vfat_hashi,

		.d_compare	= vfat_cmpi,

	},

	{

		.d_revalidate	= vfat_revalidate,

static struct dentry_operations vfat_ci_dentry_ops = {

	.d_revalidate	= vfat_revalidate_ci,

	.d_hash		= vfat_hashi,

	.d_compare	= vfat_cmpi,

	},

	{

		.d_hash		= vfat_hash,

		.d_compare	= vfat_cmp,

	},

	{

};



static struct dentry_operations vfat_dentry_ops = {

	.d_revalidate	= vfat_revalidate,

	.d_hash		= vfat_hash,

	.d_compare	= vfat_cmp,

	}

};



/* Characters that are undesirable in an MS-DOS file name */
@@ -685,29 +716,35 @@ static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry, 
	struct fat_slot_info sinfo;

	struct inode *inode;

	struct dentry *alias;

	int err, table;

	int err;



	lock_super(sb);

	table = (MSDOS_SB(sb)->options.name_check == 's') ? 2 : 0;

	dentry->d_op = &vfat_dentry_ops[table];



	err = vfat_find(dir, &dentry->d_name, &sinfo);

	if (err) {

		if (err == -ENOENT) {

			table++;

			inode = NULL;

			goto out;

		}

		goto error;

	}



	inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);

	brelse(sinfo.bh);

	if (IS_ERR(inode)) {

		err = PTR_ERR(inode);

		goto error;

	}



	alias = d_find_alias(inode);

	if (alias) {

	if (alias && !(alias->d_flags & DCACHE_DISCONNECTED)) {

		/*

		 * This inode has non DCACHE_DISCONNECTED dentry. This

		 * means, the user did ->lookup() by an another name

		 * (longname vs 8.3 alias of it) in past.

		 *

		 * Switch to new one for reason of locality if possible.

		 */

		if (d_invalidate(alias) == 0)

			dput(alias);

		else {
@@ -715,15 +752,14 @@ static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry, 
			unlock_super(sb);

			return alias;

		}



	}

out:

	unlock_super(sb);

	dentry->d_op = &vfat_dentry_ops[table];

	dentry->d_op = sb->s_root->d_op;

	dentry->d_time = dentry->d_parent->d_inode->i_version;

	dentry = d_splice_alias(inode, dentry);

	if (dentry) {

		dentry->d_op = &vfat_dentry_ops[table];

		dentry->d_op = sb->s_root->d_op;

		dentry->d_time = dentry->d_parent->d_inode->i_version;

	}

	return dentry;
@@ -1022,9 +1058,9 @@ static int vfat_fill_super(struct super_block *sb, void *data, int silent) 
		return res;



	if (MSDOS_SB(sb)->options.name_check != 's')

		sb->s_root->d_op = &vfat_dentry_ops[0];

		sb->s_root->d_op = &vfat_ci_dentry_ops;

	else

		sb->s_root->d_op = &vfat_dentry_ops[2];

		sb->s_root->d_op = &vfat_dentry_ops;



	return 0;

}