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fat: Fix/Cleanup dcache handling for vfat

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- 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: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
OGAWA Hirofumi 2008-11-06 12:53:51 -08:00 committed by Linus Torvalds
parent 068f5ae05c
commit 1b52467243
1 changed files with 80 additions and 44 deletions
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124
fs/fat/namei_vfat.c
View file

@ -24,27 +24,67 @@
#include <linux/namei.h>
#include "fat.h"
static int vfat_revalidate(struct dentry *dentry, struct nameidata *nd)
/*
* 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.
*/
static int vfat_revalidate_shortname(struct dentry *dentry)
{
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.
*/
spin_lock(&dentry->d_lock);
if (dentry->d_time != dentry->d_parent->d_inode->i_version)
ret = 0;
else {
spin_lock(&dentry->d_lock);
if (dentry->d_time != dentry->d_parent->d_inode->i_version)
ret = 0;
spin_unlock(&dentry->d_lock);
}
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,
.d_hash = vfat_hashi,
.d_compare = vfat_cmpi,
},
{
.d_hash = vfat_hash,
.d_compare = vfat_cmp,
},
{
.d_revalidate = vfat_revalidate,
.d_hash = vfat_hash,
.d_compare = vfat_cmp,
}
static struct dentry_operations vfat_ci_dentry_ops = {
.d_revalidate = vfat_revalidate_ci,
.d_hash = vfat_hashi,
.d_compare = vfat_cmpi,
};
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;
}