fs: change d_compare for rcu-walk

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.

For in-tree filesystems, this is just a mechanical change.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

2 files changed, 19 insertions, 14 deletions

diff --git a/fs/ncpfs/dir.c b/fs/ncpfs/dir.c
index e80ea4e37c48..3bcc68aed416 100644
--- a/fs/ncpfs/dir.c
+++ b/fs/ncpfs/dir.c
@@ -75,7 +75,9 @@ const struct inode_operations ncp_dir_inode_operations =
  */
 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 inode *,
+                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 =
@@ -113,10 +115,10 @@ static inline int ncp_preserve_entry_case(struct inode *i, __u32 nscreator)
 
 #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 *i)
 {
 #ifdef CONFIG_NCPFS_NFS_NS
-        return ncp_namespace(dentry->d_inode) == NW_NS_NFS;
+        return ncp_namespace(i) == NW_NS_NFS;
 #else
         return 0;
 #endif /* CONFIG_NCPFS_NFS_NS */
@@ -129,12 +131,13 @@ static inline int ncp_case_sensitive(struct dentry *dentry)
 static int 
 ncp_hash_dentry(struct dentry *dentry, struct qstr *this)
 {
-        if (!ncp_case_sensitive(dentry)) {
+        if (!ncp_case_sensitive(dentry->d_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]),
@@ -145,15 +148,17 @@ ncp_hash_dentry(struct dentry *dentry, struct qstr *this)
 }
 
 static int
-ncp_compare_dentry(struct dentry *dentry, struct qstr *a, struct qstr *b)
+ncp_compare_dentry(const struct dentry *parent, const struct inode *pinode,
+                const struct dentry *dentry, const struct inode *inode,
+                unsigned int len, const char *str, const struct qstr *name)
 {
-        if (a->len != b->len)
+        if (len != name->len)
                 return 1;
 
-        if (ncp_case_sensitive(dentry))
-                return strncmp(a->name, b->name, a->len);
+        if (ncp_case_sensitive(pinode))
+                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(pinode->i_sb), str, name->name, len);
 }
 
 /*
diff --git a/fs/ncpfs/ncplib_kernel.h b/fs/ncpfs/ncplib_kernel.h
index 3c57eca634ce..244d1b73fda7 100644
--- a/fs/ncpfs/ncplib_kernel.h
+++ b/fs/ncpfs/ncplib_kernel.h
@@ -135,7 +135,7 @@ int ncp__vol2io(struct ncp_server *, unsigned char *, unsigned int *,
                                 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 *, unsigned int *,
 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++))