[patch 1/7] vfs: mountinfo: add dentry_path()

[mszeredi@suse.cz] split big patch into managable chunks

Add the following functions:

  dentry_path()
  seq_dentry()

These are similar to d_path() and seq_path().  But instead of
calculating the path within a mount namespace, they calculate the path
from the root of the filesystem to a given dentry, ignoring mounts
completely.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/dcache.c b/fs/dcache.c
index 4345577..635c2aa 100644 (file)
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1746,6 +1746,17 @@ shouldnt_be_hashed:
        goto shouldnt_be_hashed;
 }
 
+static int prepend(char **buffer, int *buflen, const char *str,
+                         int namelen)
+{
+       *buflen -= namelen;
+       if (*buflen < 0)
+               return -ENAMETOOLONG;
+       *buffer -= namelen;
+       memcpy(*buffer, str, namelen);
+       return 0;
+}
+
 /**
  * d_path - return the path of a dentry
  * @dentry: dentry to report
@@ -1767,17 +1778,11 @@ static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt,
 {
        char * end = buffer+buflen;
        char * retval;
-       int namelen;
-
-       *--end = '\0';
-       buflen--;
-       if (!IS_ROOT(dentry) && d_unhashed(dentry)) {
-               buflen -= 10;
-               end -= 10;
-               if (buflen < 0)
+
+       prepend(&end, &buflen, "\0", 1);
+       if (!IS_ROOT(dentry) && d_unhashed(dentry) &&
+               (prepend(&end, &buflen, " (deleted)", 10) != 0))
                        goto Elong;
-               memcpy(end, " (deleted)", 10);
-       }
 
        if (buflen < 1)
                goto Elong;
@@ -1804,13 +1809,10 @@ static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt,
                }
                parent = dentry->d_parent;
                prefetch(parent);
-               namelen = dentry->d_name.len;
-               buflen -= namelen + 1;
-               if (buflen < 0)
+               if ((prepend(&end, &buflen, dentry->d_name.name,
+                               dentry->d_name.len) != 0) ||
+                   (prepend(&end, &buflen, "/", 1) != 0))
                        goto Elong;
-               end -= namelen;
-               memcpy(end, dentry->d_name.name, namelen);
-               *--end = '/';
                retval = end;
                dentry = parent;
        }
@@ -1818,12 +1820,10 @@ static char *__d_path(struct dentry *dentry, struct vfsmount *vfsmnt,
        return retval;
 
 global_root:
-       namelen = dentry->d_name.len;
-       buflen -= namelen;
-       if (buflen < 0)
+       retval += 1;    /* hit the slash */
+       if (prepend(&retval, &buflen, dentry->d_name.name,
+                   dentry->d_name.len) != 0)
                goto Elong;
-       retval -= namelen-1;    /* hit the slash */
-       memcpy(retval, dentry->d_name.name, namelen);
        return retval;
 Elong:
        return ERR_PTR(-ENAMETOOLONG);
@@ -1859,7 +1859,7 @@ char *d_path(struct path *path, char *buf, int buflen)
 
        read_lock(&current->fs->lock);
        root = current->fs->root;
-       path_get(&current->fs->root);
+       path_get(&root);
        read_unlock(&current->fs->lock);
        spin_lock(&dcache_lock);
        res = __d_path(path->dentry, path->mnt, &root, buf, buflen);
@@ -1889,6 +1889,48 @@ char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
        return memcpy(buffer, temp, sz);
 }
 
+/*
+ * Write full pathname from the root of the filesystem into the buffer.
+ */
+char *dentry_path(struct dentry *dentry, char *buf, int buflen)
+{
+       char *end = buf + buflen;
+       char *retval;
+
+       spin_lock(&dcache_lock);
+       prepend(&end, &buflen, "\0", 1);
+       if (!IS_ROOT(dentry) && d_unhashed(dentry) &&
+               (prepend(&end, &buflen, "//deleted", 9) != 0))
+                       goto Elong;
+       if (buflen < 1)
+               goto Elong;
+       /* Get '/' right */
+       retval = end-1;
+       *retval = '/';
+
+       for (;;) {
+               struct dentry *parent;
+               if (IS_ROOT(dentry))
+                       break;
+
+               parent = dentry->d_parent;
+               prefetch(parent);
+
+               if ((prepend(&end, &buflen, dentry->d_name.name,
+                               dentry->d_name.len) != 0) ||
+                   (prepend(&end, &buflen, "/", 1) != 0))
+                       goto Elong;
+
+               retval = end;
+               dentry = parent;
+       }
+       spin_unlock(&dcache_lock);
+       return retval;
+Elong:
+       spin_unlock(&dcache_lock);
+       return ERR_PTR(-ENAMETOOLONG);
+}
+
 /*
  * NOTE! The user-level library version returns a
  * character pointer. The kernel system call just
@@ -1918,9 +1960,9 @@ asmlinkage long sys_getcwd(char __user *buf, unsigned long size)
 
        read_lock(&current->fs->lock);
        pwd = current->fs->pwd;
-       path_get(&current->fs->pwd);
+       path_get(&pwd);
        root = current->fs->root;
-       path_get(&current->fs->root);
+       path_get(&root);
        read_unlock(&current->fs->lock);
 
        error = -ENOENT;

diff --git a/fs/seq_file.c b/fs/seq_file.c
index cdfd996..ae59f5a 100644 (file)
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -350,28 +350,40 @@ int seq_printf(struct seq_file *m, const char *f, ...)
 }
 EXPORT_SYMBOL(seq_printf);
 
+static char *mangle_path(char *s, char *p, char *esc)
+{
+       while (s <= p) {
+               char c = *p++;
+               if (!c) {
+                       return s;
+               } else if (!strchr(esc, c)) {
+                       *s++ = c;
+               } else if (s + 4 > p) {
+                       break;
+               } else {
+                       *s++ = '\\';
+                       *s++ = '0' + ((c & 0300) >> 6);
+                       *s++ = '0' + ((c & 070) >> 3);
+                       *s++ = '0' + (c & 07);
+               }
+       }
+       return NULL;
+}
+
+/*
+ * return the absolute path of 'dentry' residing in mount 'mnt'.
+ */
 int seq_path(struct seq_file *m, struct path *path, char *esc)
 {
        if (m->count < m->size) {
                char *s = m->buf + m->count;
                char *p = d_path(path, s, m->size - m->count);
                if (!IS_ERR(p)) {
-                       while (s <= p) {
-                               char c = *p++;
-                               if (!c) {
-                                       p = m->buf + m->count;
-                                       m->count = s - m->buf;
-                                       return s - p;
-                               } else if (!strchr(esc, c)) {
-                                       *s++ = c;
-                               } else if (s + 4 > p) {
-                                       break;
-                               } else {
-                                       *s++ = '\\';
-                                       *s++ = '0' + ((c & 0300) >> 6);
-                                       *s++ = '0' + ((c & 070) >> 3);
-                                       *s++ = '0' + (c & 07);
-                               }
+                       s = mangle_path(s, p, esc);
+                       if (s) {
+                               p = m->buf + m->count;
+                               m->count = s - m->buf;
+                               return s - p;
                        }
                }
        }
@@ -380,6 +392,27 @@ int seq_path(struct seq_file *m, struct path *path, char *esc)
 }
 EXPORT_SYMBOL(seq_path);
 
+/*
+ * returns the path of the 'dentry' from the root of its filesystem.
+ */
+int seq_dentry(struct seq_file *m, struct dentry *dentry, char *esc)
+{
+       if (m->count < m->size) {
+               char *s = m->buf + m->count;
+               char *p = dentry_path(dentry, s, m->size - m->count);
+               if (!IS_ERR(p)) {
+                       s = mangle_path(s, p, esc);
+                       if (s) {
+                               p = m->buf + m->count;
+                               m->count = s - m->buf;
+                               return s - p;
+                       }
+               }
+       }
+       m->count = m->size;
+       return -1;
+}
+
 static void *single_start(struct seq_file *p, loff_t *pos)
 {
        return NULL + (*pos == 0);

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index fabd16d..6396003 100644 (file)
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -302,6 +302,7 @@ extern int d_validate(struct dentry *, struct dentry *);
 extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
 
 extern char *d_path(struct path *, char *, int);
+extern char *dentry_path(struct dentry *, char *, int);
 
 /* Allocation counts.. */
 

diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index d65796d..11676cc 100644 (file)
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -10,6 +10,7 @@ struct seq_operations;
 struct file;
 struct path;
 struct inode;
+struct dentry;
 
 struct seq_file {
        char *buf;
@@ -44,6 +45,7 @@ int seq_printf(struct seq_file *, const char *, ...)
        __attribute__ ((format (printf,2,3)));
 
 int seq_path(struct seq_file *, struct path *, char *);
+int seq_dentry(struct seq_file *, struct dentry *, char *);
 
 int single_open(struct file *, int (*)(struct seq_file *, void *), void *);
 int single_release(struct inode *, struct file *);