[patch 5/6] fs: d_compare change for rcu-walk

From: Nick Piggin
Date: Tue Nov 09 2010 - 08:02:48 EST

Change d_compare so it may be called from lock-free RCU lookups. This
does put significant restrictions on what may be done from the callback,
however there don't seem to have been any problems with in-tree fses.
If some strange use case pops up that _really_ cannot cope with the
rcu-walk rules, we can just add new rcu-unaware callbacks, which would
cause name lookup to drop out of rcu-walk mode.

cifs and jfs contain the non-trivial changes, where they no longer
overwrite dentry name in their d_compare(), but rather use the
d_revalidate() method for ensuring case preservation in the presence
of negative dentries, taken from fatfs.

Signed-off-by: Nick Piggin <npiggin@xxxxxxxxx>

---
Documentation/filesystems/Locking | 4 +
Documentation/filesystems/porting | 7 +++
Documentation/filesystems/vfs.txt | 25 +++++++++-
fs/adfs/dir.c | 8 ++-
fs/affs/namei.c | 44 +++++++++++--------
fs/cifs/dir.c | 52 ++++++++++++----------
fs/dcache.c | 4 +
fs/fat/namei_msdos.c | 15 +++---
fs/fat/namei_vfat.c | 39 +++++++++++-----
fs/hfs/hfs_fs.h | 4 +
fs/hfs/string.c | 14 +++---
fs/hfsplus/hfsplus_fs.h | 4 +
fs/hfsplus/unicode.c | 14 +++---
fs/hpfs/dentry.c | 21 +++++----
fs/isofs/inode.c | 88 ++++++++++++++++++--------------------
fs/isofs/namei.c | 3 -
fs/jfs/namei.c | 53 +++++++++++++++++-----
fs/ncpfs/dir.c | 29 ++++++++----
fs/ncpfs/ncplib_kernel.h | 8 +--
fs/proc/proc_sysctl.c | 12 ++---
include/linux/dcache.h | 12 ++---
include/linux/ncp_fs.h | 4 -
22 files changed, 286 insertions(+), 178 deletions(-)

Index: linux-2.6/fs/adfs/dir.c
===================================================================
--- linux-2.6.orig/fs/adfs/dir.c 2010-11-09 22:10:59.000000000 +1100
+++ linux-2.6/fs/adfs/dir.c 2010-11-09 23:22:50.000000000 +1100
@@ -237,17 +237,19 @@ adfs_hash(struct dentry *parent, struct
* requirements of the underlying filesystem.
*/
static int
-adfs_compare(struct dentry *parent, struct qstr *entry, struct qstr *name)
+adfs_compare(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
int i;

- if (entry->len != name->len)
+ if (len != name->len)
return 1;

for (i = 0; i < name->len; i++) {
char a, b;

- a = entry->name[i];
+ a = str[i];
b = name->name[i];

if (a >= 'A' && a <= 'Z')
Index: linux-2.6/fs/cifs/dir.c
===================================================================
--- linux-2.6.orig/fs/cifs/dir.c 2010-11-09 22:10:58.000000000 +1100
+++ linux-2.6/fs/cifs/dir.c 2010-11-09 23:22:49.000000000 +1100
@@ -656,22 +656,34 @@ cifs_lookup(struct inode *parent_dir_ino
static int
cifs_d_revalidate(struct dentry *direntry, struct nameidata *nd)
{
- int isValid = 1;
-
if (direntry->d_inode) {
if (cifs_revalidate_dentry(direntry))
return 0;
- } else {
- cFYI(1, "neg dentry 0x%p name = %s",
- direntry, direntry->d_name.name);
- if (time_after(jiffies, direntry->d_time + HZ) ||
- !lookupCacheEnabled) {
- d_drop(direntry);
- isValid = 0;
- }
+ else
+ 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 | LOOKUP_RENAME_TARGET))
+ return 0;
}

- return isValid;
+ if (time_after(jiffies, direntry->d_time + HZ) || !lookupCacheEnabled)
+ return 0;
+
+ return 1;
}

/* static int cifs_d_delete(struct dentry *direntry)
@@ -703,21 +715,15 @@ static int cifs_ci_hash(struct dentry *d
return 0;
}

-static int cifs_ci_compare(struct dentry *dentry, struct qstr *a,
- struct qstr *b)
+static int cifs_ci_compare(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- struct nls_table *codepage = CIFS_SB(dentry->d_inode->i_sb)->local_nls;
+ struct nls_table *codepage = CIFS_SB(inode->i_sb)->local_nls;

- if ((a->len == b->len) &&
- (nls_strnicmp(codepage, a->name, b->name, a->len) == 0)) {
- /*
- * To preserve case, don't let an existing negative dentry's
- * case take precedence. If a is not a negative dentry, this
- * should have no side effects
- */
- memcpy((void *)a->name, b->name, a->len);
+ if ((name->len == len) &&
+ (nls_strnicmp(codepage, name->name, str, len) == 0))
return 0;
- }
return 1;
}

Index: linux-2.6/fs/dcache.c
===================================================================
--- linux-2.6.orig/fs/dcache.c 2010-11-09 22:11:10.000000000 +1100
+++ linux-2.6/fs/dcache.c 2010-11-09 23:22:49.000000000 +1100
@@ -1433,7 +1433,9 @@ struct dentry * __d_lookup(struct dentry
*/
qstr = &dentry->d_name;
if (parent->d_op && parent->d_op->d_compare) {
- if (parent->d_op->d_compare(parent, qstr, name))
+ if (parent->d_op->d_compare(parent,
+ dentry, dentry->d_inode,
+ qstr->len, qstr->name, name))
goto next;
} else {
if (qstr->len != len)
Index: linux-2.6/fs/fat/namei_msdos.c
===================================================================
--- linux-2.6.orig/fs/fat/namei_msdos.c 2010-11-09 22:10:58.000000000 +1100
+++ linux-2.6/fs/fat/namei_msdos.c 2010-11-09 23:22:49.000000000 +1100
@@ -164,16 +164,19 @@ static int msdos_hash(struct dentry *den
* Compare two msdos names. If either of the names are invalid,
* we fall back to doing the standard name comparison.
*/
-static int msdos_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b)
+static int msdos_cmp(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str,
+ const struct qstr *name)
{
- struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options;
+ struct fat_mount_options *options = &MSDOS_SB(parent->d_sb)->options;
unsigned char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME];
int error;

- error = msdos_format_name(a->name, a->len, a_msdos_name, options);
+ error = msdos_format_name(name->name, name->len, a_msdos_name, options);
if (error)
goto old_compare;
- error = msdos_format_name(b->name, b->len, b_msdos_name, options);
+ error = msdos_format_name(str, len, b_msdos_name, options);
if (error)
goto old_compare;
error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME);
@@ -182,8 +185,8 @@ static int msdos_cmp(struct dentry *dent

old_compare:
error = 1;
- if (a->len == b->len)
- error = memcmp(a->name, b->name, a->len);
+ if (name->len == len)
+ error = memcmp(name->name, str, len);
goto out;
}

Index: linux-2.6/fs/fat/namei_vfat.c
===================================================================
--- linux-2.6.orig/fs/fat/namei_vfat.c 2010-11-09 22:10:58.000000000 +1100
+++ linux-2.6/fs/fat/namei_vfat.c 2010-11-09 23:22:49.000000000 +1100
@@ -85,15 +85,18 @@ static int vfat_revalidate_ci(struct den
}

/* returns the length of a struct qstr, ignoring trailing dots */
-static unsigned int vfat_striptail_len(struct qstr *qstr)
+static unsigned int __vfat_striptail_len(unsigned int len, const char *name)
{
- unsigned int len = qstr->len;
-
- while (len && qstr->name[len - 1] == '.')
+ while (len && name[len - 1] == '.')
len--;
return len;
}

+static unsigned int vfat_striptail_len(const struct qstr *qstr)
+{
+ return __vfat_striptail_len(qstr->len, qstr->name);
+}
+
/*
* Compute the hash for the vfat name corresponding to the dentry.
* Note: if the name is invalid, we leave the hash code unchanged so
@@ -133,16 +136,18 @@ static int vfat_hashi(struct dentry *den
/*
* Case insensitive compare of two vfat names.
*/
-static int vfat_cmpi(struct dentry *dentry, struct qstr *a, struct qstr *b)
+static int vfat_cmpi(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- struct nls_table *t = MSDOS_SB(dentry->d_inode->i_sb)->nls_io;
+ struct nls_table *t = MSDOS_SB(inode->i_sb)->nls_io;
unsigned int alen, blen;

/* A filename cannot end in '.' or we treat it like it has none */
- alen = vfat_striptail_len(a);
- blen = vfat_striptail_len(b);
+ alen = vfat_striptail_len(name);
+ blen = __vfat_striptail_len(len, str);
if (alen == blen) {
- if (nls_strnicmp(t, a->name, b->name, alen) == 0)
+ if (nls_strnicmp(t, name->name, str, alen) == 0)
return 0;
}
return 1;
@@ -151,15 +156,17 @@ static int vfat_cmpi(struct dentry *dent
/*
* Case sensitive compare of two vfat names.
*/
-static int vfat_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b)
+static int vfat_cmp(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
unsigned int alen, blen;

/* A filename cannot end in '.' or we treat it like it has none */
- alen = vfat_striptail_len(a);
- blen = vfat_striptail_len(b);
+ alen = vfat_striptail_len(name);
+ blen = __vfat_striptail_len(len, str);
if (alen == blen) {
- if (strncmp(a->name, b->name, alen) == 0)
+ if (strncmp(name->name, str, alen) == 0)
return 0;
}
return 1;
@@ -780,6 +787,12 @@ static int vfat_create(struct inode *dir
struct timespec ts;
int err;

+ /*
+ * To preserve case, don't let an existing negative dentry's case
+ * take precedence.
+ */
+ memcpy((void *)dentry->d_name.name, nd->last.name, dentry->d_name.len);
+
lock_super(sb);

ts = CURRENT_TIME_SEC;
Index: linux-2.6/fs/isofs/inode.c
===================================================================
--- linux-2.6.orig/fs/isofs/inode.c 2010-11-09 22:11:10.000000000 +1100
+++ linux-2.6/fs/isofs/inode.c 2010-11-09 23:22:50.000000000 +1100
@@ -28,14 +28,22 @@

static int isofs_hashi(struct dentry *parent, struct qstr *qstr);
static int isofs_hash(struct dentry *parent, struct qstr *qstr);
-static int isofs_dentry_cmpi(struct dentry *dentry, struct qstr *a, struct qstr *b);
-static int isofs_dentry_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b);
+static int isofs_dentry_cmpi(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name);
+static int isofs_dentry_cmp(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name);

#ifdef CONFIG_JOLIET
static int isofs_hashi_ms(struct dentry *parent, struct qstr *qstr);
static int isofs_hash_ms(struct dentry *parent, struct qstr *qstr);
-static int isofs_dentry_cmpi_ms(struct dentry *dentry, struct qstr *a, struct qstr *b);
-static int isofs_dentry_cmp_ms(struct dentry *dentry, struct qstr *a, struct qstr *b);
+static int isofs_dentry_cmpi_ms(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name);
+static int isofs_dentry_cmp_ms(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name);
#endif

static void isofs_put_super(struct super_block *sb)
@@ -213,49 +221,31 @@ isofs_hashi_common(struct dentry *dentry
}

/*
- * Case insensitive compare of two isofs names.
+ * Compare of two isofs names.
*/
-static int isofs_dentry_cmpi_common(struct dentry *dentry, struct qstr *a,
- struct qstr *b, int ms)
+static int isofs_dentry_cmp_common(
+ unsigned int len, const char *str,
+ const struct qstr *name, int ms, int ci)
{
int alen, blen;

/* A filename cannot end in '.' or we treat it like it has none */
- alen = a->len;
- blen = b->len;
+ alen = name->len;
+ blen = len;
if (ms) {
- while (alen && a->name[alen-1] == '.')
+ while (alen && name->name[alen-1] == '.')
alen--;
- while (blen && b->name[blen-1] == '.')
+ while (blen && str[blen-1] == '.')
blen--;
}
if (alen == blen) {
- if (strnicmp(a->name, b->name, alen) == 0)
- return 0;
- }
- return 1;
-}
-
-/*
- * Case sensitive compare of two isofs names.
- */
-static int isofs_dentry_cmp_common(struct dentry *dentry, struct qstr *a,
- struct qstr *b, int ms)
-{
- int alen, blen;
-
- /* A filename cannot end in '.' or we treat it like it has none */
- alen = a->len;
- blen = b->len;
- if (ms) {
- while (alen && a->name[alen-1] == '.')
- alen--;
- while (blen && b->name[blen-1] == '.')
- blen--;
- }
- if (alen == blen) {
- if (strncmp(a->name, b->name, alen) == 0)
- return 0;
+ if (ci) {
+ if (strnicmp(name->name, str, alen) == 0)
+ return 0;
+ } else {
+ if (strncmp(name->name, str, alen) == 0)
+ return 0;
+ }
}
return 1;
}
@@ -273,15 +263,19 @@ isofs_hashi(struct dentry *dentry, struc
}

static int
-isofs_dentry_cmp(struct dentry *dentry,struct qstr *a,struct qstr *b)
+isofs_dentry_cmp(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- return isofs_dentry_cmp_common(dentry, a, b, 0);
+ return isofs_dentry_cmp_common(len, str, name, 0, 0);
}

static int
-isofs_dentry_cmpi(struct dentry *dentry,struct qstr *a,struct qstr *b)
+isofs_dentry_cmpi(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- return isofs_dentry_cmpi_common(dentry, a, b, 0);
+ return isofs_dentry_cmp_common(len, str, name, 0, 1);
}

#ifdef CONFIG_JOLIET
@@ -298,15 +292,19 @@ isofs_hashi_ms(struct dentry *dentry, st
}

static int
-isofs_dentry_cmp_ms(struct dentry *dentry,struct qstr *a,struct qstr *b)
+isofs_dentry_cmp_ms(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- return isofs_dentry_cmp_common(dentry, a, b, 1);
+ return isofs_dentry_cmp_common(len, str, name, 1, 0);
}

static int
-isofs_dentry_cmpi_ms(struct dentry *dentry,struct qstr *a,struct qstr *b)
+isofs_dentry_cmpi_ms(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- return isofs_dentry_cmpi_common(dentry, a, b, 1);
+ return isofs_dentry_cmp_common(len, str, name, 1, 1);
}
#endif

Index: linux-2.6/fs/proc/proc_sysctl.c
===================================================================
--- linux-2.6.orig/fs/proc/proc_sysctl.c 2010-11-09 22:11:10.000000000 +1100
+++ linux-2.6/fs/proc/proc_sysctl.c 2010-11-09 22:11:10.000000000 +1100
@@ -397,15 +397,15 @@ static int proc_sys_delete(const struct
return !!PROC_I(dentry->d_inode)->sysctl->unregistering;
}

-static int proc_sys_compare(struct dentry *dir, struct qstr *qstr,
- struct qstr *name)
+static int proc_sys_compare(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- struct dentry *dentry = container_of(qstr, struct dentry, d_name);
- if (qstr->len != name->len)
+ if (name->len != len)
return 1;
- if (memcmp(qstr->name, name->name, name->len))
+ if (memcmp(name->name, str, len))
return 1;
- return !sysctl_is_seen(PROC_I(dentry->d_inode)->sysctl);
+ return !sysctl_is_seen(PROC_I(inode)->sysctl);
}

static const struct dentry_operations proc_sys_dentry_operations = {
Index: linux-2.6/include/linux/dcache.h
===================================================================
--- linux-2.6.orig/include/linux/dcache.h 2010-11-09 22:11:10.000000000 +1100
+++ linux-2.6/include/linux/dcache.h 2010-11-09 23:22:49.000000000 +1100
@@ -134,7 +134,9 @@ enum dentry_d_lock_class
struct dentry_operations {
int (*d_revalidate)(struct dentry *, struct nameidata *);
int (*d_hash)(struct dentry *, struct qstr *);
- int (*d_compare)(struct dentry *, struct qstr *, struct qstr *);
+ int (*d_compare)(const struct dentry *,
+ const struct dentry *, const struct inode *,
+ unsigned int, const char *, const struct qstr *);
int (*d_delete)(const struct dentry *);
void (*d_release)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
@@ -145,12 +147,8 @@ struct dentry_operations {
* Locking rules for dentry_operations callbacks are to be found in
* Documentation/filesystems/Locking. Keep it updated!
*
- * the dentry parameter passed to d_hash and d_compare is the parent
- * directory of the entries to be compared. It is used in case these
- * functions need any directory specific information for determining
- * equivalency classes. Using the dentry itself might not work, as it
- * might be a negative dentry which has no information associated with
- * it.
+ * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
+ * Keep it updated too!
*/

/* d_flags entries */
Index: linux-2.6/fs/affs/namei.c
===================================================================
--- linux-2.6.orig/fs/affs/namei.c 2010-11-09 22:10:58.000000000 +1100
+++ linux-2.6/fs/affs/namei.c 2010-11-09 23:22:49.000000000 +1100
@@ -14,10 +14,14 @@ typedef int (*toupper_t)(int);

static int affs_toupper(int ch);
static int affs_hash_dentry(struct dentry *, struct qstr *);
-static int affs_compare_dentry(struct dentry *, struct qstr *, struct qstr *);
+static int affs_compare_dentry(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name);
static int affs_intl_toupper(int ch);
static int affs_intl_hash_dentry(struct dentry *, struct qstr *);
-static int affs_intl_compare_dentry(struct dentry *, struct qstr *, struct qstr *);
+static int affs_intl_compare_dentry(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name);

const struct dentry_operations affs_dentry_operations = {
.d_hash = affs_hash_dentry,
@@ -88,29 +92,29 @@ affs_intl_hash_dentry(struct dentry *den
return __affs_hash_dentry(dentry, qstr, affs_intl_toupper);
}

-static inline int
-__affs_compare_dentry(struct dentry *dentry, struct qstr *a, struct qstr *b, toupper_t toupper)
+static inline int __affs_compare_dentry(unsigned int len,
+ const char *str, const struct qstr *name, toupper_t toupper)
{
- const u8 *aname = a->name;
- const u8 *bname = b->name;
- int len;
+ const u8 *aname = str;
+ const u8 *bname = name->name;

- /* 'a' is the qstr of an already existing dentry, so the name
- * must be valid. 'b' must be validated first.
+ /*
+ * 'str' is the name of an already existing dentry, so the name
+ * must be valid. 'name' must be validated first.
*/

- if (affs_check_name(b->name,b->len))
+ if (affs_check_name(name->name, name->len))
return 1;

- /* If the names are longer than the allowed 30 chars,
+ /*
+ * If the names are longer than the allowed 30 chars,
* the excess is ignored, so their length may differ.
*/
- len = a->len;
if (len >= 30) {
- if (b->len < 30)
+ if (name->len < 30)
return 1;
len = 30;
- } else if (len != b->len)
+ } else if (len != name->len)
return 1;

for (; len > 0; len--)
@@ -121,14 +125,18 @@ __affs_compare_dentry(struct dentry *den
}

static int
-affs_compare_dentry(struct dentry *dentry, struct qstr *a, struct qstr *b)
+affs_compare_dentry(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- return __affs_compare_dentry(dentry, a, b, affs_toupper);
+ return __affs_compare_dentry(len, str, name, affs_toupper);
}
static int
-affs_intl_compare_dentry(struct dentry *dentry, struct qstr *a, struct qstr *b)
+affs_intl_compare_dentry(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- return __affs_compare_dentry(dentry, a, b, affs_intl_toupper);
+ return __affs_compare_dentry(len, str, name, affs_intl_toupper);
}

/*
Index: linux-2.6/fs/hfs/hfs_fs.h
===================================================================
--- linux-2.6.orig/fs/hfs/hfs_fs.h 2010-11-09 22:10:58.000000000 +1100
+++ linux-2.6/fs/hfs/hfs_fs.h 2010-11-09 23:22:49.000000000 +1100
@@ -216,7 +216,9 @@ extern const struct dentry_operations hf
extern int hfs_hash_dentry(struct dentry *, struct qstr *);
extern int hfs_strcmp(const unsigned char *, unsigned int,
const unsigned char *, unsigned int);
-extern int hfs_compare_dentry(struct dentry *, struct qstr *, struct qstr *);
+extern int hfs_compare_dentry(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name);

/* trans.c */
extern void hfs_asc2mac(struct super_block *, struct hfs_name *, struct qstr *);
Index: linux-2.6/fs/hfs/string.c
===================================================================
--- linux-2.6.orig/fs/hfs/string.c 2010-11-09 22:10:58.000000000 +1100
+++ linux-2.6/fs/hfs/string.c 2010-11-09 23:22:49.000000000 +1100
@@ -92,21 +92,21 @@ int hfs_strcmp(const unsigned char *s1,
* Test for equality of two strings in the HFS filename character ordering.
* return 1 on failure and 0 on success
*/
-int hfs_compare_dentry(struct dentry *dentry, struct qstr *s1, struct qstr *s2)
+int hfs_compare_dentry(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
const unsigned char *n1, *n2;
- int len;

- len = s1->len;
if (len >= HFS_NAMELEN) {
- if (s2->len < HFS_NAMELEN)
+ if (name->len < HFS_NAMELEN)
return 1;
len = HFS_NAMELEN;
- } else if (len != s2->len)
+ } else if (len != name->len)
return 1;

- n1 = s1->name;
- n2 = s2->name;
+ n1 = str;
+ n2 = name->name;
while (len--) {
if (caseorder[*n1++] != caseorder[*n2++])
return 1;
Index: linux-2.6/fs/hfsplus/hfsplus_fs.h
===================================================================
--- linux-2.6.orig/fs/hfsplus/hfsplus_fs.h 2010-11-09 22:10:59.000000000 +1100
+++ linux-2.6/fs/hfsplus/hfsplus_fs.h 2010-11-09 23:22:50.000000000 +1100
@@ -380,7 +380,9 @@ int hfsplus_strcmp(const struct hfsplus_
int hfsplus_uni2asc(struct super_block *, const struct hfsplus_unistr *, char *, int *);
int hfsplus_asc2uni(struct super_block *, struct hfsplus_unistr *, const char *, int);
int hfsplus_hash_dentry(struct dentry *dentry, struct qstr *str);
-int hfsplus_compare_dentry(struct dentry *dentry, struct qstr *s1, struct qstr *s2);
+int hfsplus_compare_dentry(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name);

/* wrapper.c */
int hfsplus_read_wrapper(struct super_block *);
Index: linux-2.6/fs/hfsplus/unicode.c
===================================================================
--- linux-2.6.orig/fs/hfsplus/unicode.c 2010-11-09 22:10:59.000000000 +1100
+++ linux-2.6/fs/hfsplus/unicode.c 2010-11-09 23:22:50.000000000 +1100
@@ -363,9 +363,11 @@ int hfsplus_hash_dentry(struct dentry *d
* Composed unicode characters are decomposed and case-folding is performed
* if the appropriate bits are (un)set on the superblock.
*/
-int hfsplus_compare_dentry(struct dentry *dentry, struct qstr *s1, struct qstr *s2)
+int hfsplus_compare_dentry(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- struct super_block *sb = dentry->d_sb;
+ struct super_block *sb = parent->d_sb;
int casefold, decompose, size;
int dsize1, dsize2, len1, len2;
const u16 *dstr1, *dstr2;
@@ -375,10 +377,10 @@ int hfsplus_compare_dentry(struct dentry

casefold = test_bit(HFSPLUS_SB_CASEFOLD, &HFSPLUS_SB(sb)->flags);
decompose = !test_bit(HFSPLUS_SB_NODECOMPOSE, &HFSPLUS_SB(sb)->flags);
- astr1 = s1->name;
- len1 = s1->len;
- astr2 = s2->name;
- len2 = s2->len;
+ astr1 = str;
+ len1 = len;
+ astr2 = name->name;
+ len2 = name->len;
dsize1 = dsize2 = 0;
dstr1 = dstr2 = NULL;

Index: linux-2.6/fs/hpfs/dentry.c
===================================================================
--- linux-2.6.orig/fs/hpfs/dentry.c 2010-11-09 22:10:58.000000000 +1100
+++ linux-2.6/fs/hpfs/dentry.c 2010-11-09 23:22:49.000000000 +1100
@@ -34,19 +34,24 @@ static int hpfs_hash_dentry(struct dentr
return 0;
}

-static int hpfs_compare_dentry(struct dentry *dentry, struct qstr *a, struct qstr *b)
+static int hpfs_compare_dentry(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- unsigned al=a->len;
- unsigned bl=b->len;
- hpfs_adjust_length(a->name, &al);
+ unsigned al = len;
+ unsigned bl = name->len;
+
+ hpfs_adjust_length(str, &al);
/*hpfs_adjust_length(b->name, &bl);*/
- /* 'a' is the qstr of an already existing dentry, so the name
- * must be valid. 'b' must be validated first.
+
+ /*
+ * 'str' is the nane of an already existing dentry, so the name
+ * must be valid. 'name' must be validated first.
*/

- if (hpfs_chk_name(b->name, &bl))
+ if (hpfs_chk_name(name->name, &bl))
return 1;
- if (hpfs_compare_names(dentry->d_sb, a->name, al, b->name, bl, 0))
+ if (hpfs_compare_names(parent->d_sb, str, al, name->name, bl, 0))
return 1;
return 0;
}
Index: linux-2.6/fs/jfs/namei.c
===================================================================
--- linux-2.6.orig/fs/jfs/namei.c 2010-11-09 22:10:59.000000000 +1100
+++ linux-2.6/fs/jfs/namei.c 2010-11-09 23:22:50.000000000 +1100
@@ -18,6 +18,7 @@
*/

#include <linux/fs.h>
+#include <linux/namei.h>
#include <linux/ctype.h>
#include <linux/quotaops.h>
#include <linux/exportfs.h>
@@ -1586,32 +1587,60 @@ static int jfs_ci_hash(struct dentry *di
return 0;
}

-static int jfs_ci_compare(struct dentry *dir, struct qstr *a, struct qstr *b)
+static int jfs_ci_compare(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
int i, result = 1;

- if (a->len != b->len)
+ if (len != name->len)
goto out;
- for (i=0; i < a->len; i++) {
- if (tolower(a->name[i]) != tolower(b->name[i]))
+ for (i=0; i < len; i++) {
+ if (tolower(str[i]) != tolower(name->name[i]))
goto out;
}
result = 0;
+out:
+ return result;
+}

+static int jfs_ci_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
/*
- * We want creates to preserve case. A negative dentry, a, that
- * has a different case than b may cause a new entry to be created
- * with the wrong case. Since we can't tell if a comes from a negative
- * dentry, we blindly replace it with b. This should be harmless if
- * a is not a negative dentry.
+ * 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.
*/
- memcpy((unsigned char *)a->name, b->name, a->len);
-out:
- return result;
+ 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 | LOOKUP_RENAME_TARGET))
+ return 0;
+ }
+ return 1;
}

const struct dentry_operations jfs_ci_dentry_operations =
{
.d_hash = jfs_ci_hash,
.d_compare = jfs_ci_compare,
+ .d_revalidate = jfs_ci_revalidate,
};
Index: linux-2.6/fs/ncpfs/dir.c
===================================================================
--- linux-2.6.orig/fs/ncpfs/dir.c 2010-11-09 22:11:10.000000000 +1100
+++ linux-2.6/fs/ncpfs/dir.c 2010-11-09 23:22:49.000000000 +1100
@@ -76,7 +76,9 @@ const struct inode_operations ncp_dir_in
*/
static int ncp_lookup_validate(struct dentry *, struct nameidata *);
static int ncp_hash_dentry(struct dentry *, struct qstr *);
-static int ncp_compare_dentry (struct dentry *, struct qstr *, struct qstr *);
+static int ncp_compare_dentry(const struct dentry *,
+ const struct dentry *, const struct inode *,
+ unsigned int, const char *, const struct qstr *);
static int ncp_delete_dentry(const struct dentry *);

static const struct dentry_operations ncp_dentry_operations =
@@ -114,10 +116,10 @@ static inline int ncp_preserve_entry_cas

#define ncp_preserve_case(i) (ncp_namespace(i) != NW_NS_DOS)

-static inline int ncp_case_sensitive(struct dentry *dentry)
+static inline int ncp_case_sensitive(const struct inode *inode)
{
#ifdef CONFIG_NCPFS_NFS_NS
- return ncp_namespace(dentry->d_inode) == NW_NS_NFS;
+ return ncp_namespace(inode) == NW_NS_NFS;
#else
return 0;
#endif /* CONFIG_NCPFS_NFS_NS */
@@ -130,12 +132,15 @@ static inline int ncp_case_sensitive(str
static int
ncp_hash_dentry(struct dentry *dentry, struct qstr *this)
{
- if (!ncp_case_sensitive(dentry)) {
+ struct inode *inode = dentry->d_inode;
+
+ if (!ncp_case_sensitive(inode)) {
+ struct super_block *sb = dentry->d_sb;
struct nls_table *t;
unsigned long hash;
int i;

- t = NCP_IO_TABLE(dentry);
+ t = NCP_IO_TABLE(sb);
hash = init_name_hash();
for (i=0; i<this->len ; i++)
hash = partial_name_hash(ncp_tolower(t, this->name[i]),
@@ -146,15 +151,19 @@ ncp_hash_dentry(struct dentry *dentry, s
}

static int
-ncp_compare_dentry(struct dentry *dentry, struct qstr *a, struct qstr *b)
+ncp_compare_dentry(const struct dentry *parent,
+ const struct dentry *dentry, const struct inode *inode,
+ unsigned int len, const char *str, const struct qstr *name)
{
- if (a->len != b->len)
+ struct super_block *sb = dentry->d_sb;
+
+ if (len != name->len)
return 1;

- if (ncp_case_sensitive(dentry))
- return strncmp(a->name, b->name, a->len);
+ if (ncp_case_sensitive(inode))
+ return strncmp(str, name->name, len);

- return ncp_strnicmp(NCP_IO_TABLE(dentry), a->name, b->name, a->len);
+ return ncp_strnicmp(NCP_IO_TABLE(sb), str, name->name, len);
}

/*
Index: linux-2.6/fs/ncpfs/ncplib_kernel.h
===================================================================
--- linux-2.6.orig/fs/ncpfs/ncplib_kernel.h 2010-11-09 22:10:58.000000000 +1100
+++ linux-2.6/fs/ncpfs/ncplib_kernel.h 2010-11-09 22:11:10.000000000 +1100
@@ -135,7 +135,7 @@ int ncp__vol2io(struct ncp_server *, uns
const unsigned char *, unsigned int, int);

#define NCP_ESC ':'
-#define NCP_IO_TABLE(dentry) (NCP_SERVER((dentry)->d_inode)->nls_io)
+#define NCP_IO_TABLE(sb) (NCP_SBP(sb)->nls_io)
#define ncp_tolower(t, c) nls_tolower(t, c)
#define ncp_toupper(t, c) nls_toupper(t, c)
#define ncp_strnicmp(t, s1, s2, len) \
@@ -150,15 +150,15 @@ int ncp__io2vol(unsigned char *, unsigne
int ncp__vol2io(unsigned char *, unsigned int *,
const unsigned char *, unsigned int, int);

-#define NCP_IO_TABLE(dentry) NULL
+#define NCP_IO_TABLE(sb) NULL
#define ncp_tolower(t, c) tolower(c)
#define ncp_toupper(t, c) toupper(c)
#define ncp_io2vol(S,m,i,n,k,U) ncp__io2vol(m,i,n,k,U)
#define ncp_vol2io(S,m,i,n,k,U) ncp__vol2io(m,i,n,k,U)


-static inline int ncp_strnicmp(struct nls_table *t, const unsigned char *s1,
- const unsigned char *s2, int len)
+static inline int ncp_strnicmp(const struct nls_table *t,
+ const unsigned char *s1, const unsigned char *s2, int len)
{
while (len--) {
if (tolower(*s1++) != tolower(*s2++))
Index: linux-2.6/Documentation/filesystems/vfs.txt
===================================================================
--- linux-2.6.orig/Documentation/filesystems/vfs.txt 2010-11-09 22:11:10.000000000 +1100
+++ linux-2.6/Documentation/filesystems/vfs.txt 2010-11-09 23:22:49.000000000 +1100
@@ -842,7 +842,9 @@ the VFS uses a default. As of kernel 2.6
struct dentry_operations {
int (*d_revalidate)(struct dentry *, struct nameidata *);
int (*d_hash)(struct dentry *, struct qstr *);
- int (*d_compare)(struct dentry *, struct qstr *, struct qstr *);
+ int (*d_compare)(const struct dentry *,
+ const struct dentry *, const struct inode *,
+ unsigned int, const char *, const struct qstr *);
int (*d_delete)(const struct dentry *);
void (*d_release)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
@@ -854,9 +856,26 @@ struct dentry_operations {
dcache. Most filesystems leave this as NULL, because all their
dentries in the dcache are valid

- d_hash: called when the VFS adds a dentry to the hash table
+ d_hash: called when the VFS adds a dentry to the hash table. The first
+ dentry passed to d_hash is the parent directory that the name is
+ to be hashed into.

- d_compare: called when a dentry should be compared with another
+ d_compare: called to compare a dentry name with a given name. The first
+ dentry is the parent of the dentry to be compared, the second is
+ the dentry itself. inode, len, and name string are properties of
+ the dentry to be compared. qstr is the name to compare it with.
+
+ Must be constant and idempotent, and should not take locks if
+ possible, and should not or store into the dentry or inodes.
+ Should not dereference pointers outside the dentry or inodes without
+ lots of care (eg. d_parent, d_inode shouldn't be used).
+
+ However, our vfsmount is pinned, and RCU held, so the dentries and
+ inodes won't disappear, neither will our sb or filesystem module.
+ ->i_sb and ->d_sb may be used.
+
+ It is a tricky calling convention because it needs to be called under
+ "rcu-walk", ie. without any locks or references on things.

d_delete: called when the last reference to a dentry is dropped and the
dcache is deciding whether or not to cache it. Return 1 to delete
Index: linux-2.6/fs/isofs/namei.c
===================================================================
--- linux-2.6.orig/fs/isofs/namei.c 2010-11-09 22:10:59.000000000 +1100
+++ linux-2.6/fs/isofs/namei.c 2010-11-09 22:11:10.000000000 +1100
@@ -37,7 +37,8 @@ isofs_cmp(struct dentry *dentry, const c

qstr.name = compare;
qstr.len = dlen;
- return dentry->d_op->d_compare(dentry, &dentry->d_name, &qstr);
+ return dentry->d_op->d_compare(NULL, NULL, NULL,
+ dentry->d_name.len, dentry->d_name.name, &qstr);
}

/*
Index: linux-2.6/include/linux/ncp_fs.h
===================================================================
--- linux-2.6.orig/include/linux/ncp_fs.h 2010-11-09 22:10:58.000000000 +1100
+++ linux-2.6/include/linux/ncp_fs.h 2010-11-09 22:11:10.000000000 +1100
@@ -184,13 +184,13 @@ struct ncp_entry_info {
__u8 file_handle[6];
};

-static inline struct ncp_server *NCP_SBP(struct super_block *sb)
+static inline struct ncp_server *NCP_SBP(const struct super_block *sb)
{
return sb->s_fs_info;
}

#define NCP_SERVER(inode) NCP_SBP((inode)->i_sb)
-static inline struct ncp_inode_info *NCP_FINFO(struct inode *inode)
+static inline struct ncp_inode_info *NCP_FINFO(const struct inode *inode)
{
return container_of(inode, struct ncp_inode_info, vfs_inode);
}
Index: linux-2.6/Documentation/filesystems/Locking
===================================================================
--- linux-2.6.orig/Documentation/filesystems/Locking 2010-11-09 22:10:59.000000000 +1100
+++ linux-2.6/Documentation/filesystems/Locking 2010-11-09 23:22:49.000000000 +1100
@@ -11,7 +11,9 @@ be able to use diff(1).
prototypes:
int (*d_revalidate)(struct dentry *, int);
int (*d_hash) (struct dentry *, struct qstr *);
- int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
+ int (*d_compare)(const struct dentry *,
+ const struct dentry *, const struct inode *,
+ unsigned int, const char *, const struct qstr *);
int (*d_delete)(struct dentry *);
void (*d_release)(struct dentry *);
void (*d_iput)(struct dentry *, struct inode *);
Index: linux-2.6/Documentation/filesystems/porting
===================================================================
--- linux-2.6.orig/Documentation/filesystems/porting 2010-11-09 22:11:10.000000000 +1100
+++ linux-2.6/Documentation/filesystems/porting 2010-11-09 23:22:49.000000000 +1100
@@ -337,3 +337,10 @@ must be done in the RCU callback.
unreferenced dentries, and is now only called when the dentry refcount goes to
0. Even on 0 refcount transition, it must be able to tolerate being called 0, 1,
or more times (eg. constant, idempotent).
+
+---
+[mandatory]
+
+ .d_compare() calling convention and locking rules are significantly
+changed. Read updated documentation in Documentation/filesystems/vfs.txt (and
+look at examples of other filesystems) for guidance.
--
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