1 files changed, 92 insertions, 21 deletions

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 853770274f20..3f54dbd6c49b 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -25,6 +25,7 @@
  *      into the buffer.  In case of error ->start() and ->next() return
  *      ERR_PTR(error).  In the end of sequence they return %NULL. ->show()
  *      returns 0 in case of success and negative number in case of error.
+ *      Returning SEQ_SKIP means "discard this element and move on".
  */
 int seq_open(struct file *file, const struct seq_operations *op)
 {
@@ -114,8 +115,10 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
                 if (!p || IS_ERR(p))
                         break;
                 err = m->op->show(m, p);
-                if (err)
+                if (err < 0)
                         break;
+                if (unlikely(err))
+                        m->count = 0;
                 if (m->count < m->size)
                         goto Fill;
                 m->op->stop(m, p);
@@ -140,9 +143,10 @@ Fill:
                         break;
                 }
                 err = m->op->show(m, p);
-                if (err || m->count == m->size) {
+                if (m->count == m->size || err) {
                         m->count = offs;
-                        break;
+                        if (likely(err <= 0))
+                                break;
                 }
                 pos = next;
         }
@@ -199,8 +203,12 @@ static int traverse(struct seq_file *m, loff_t offset)
                 if (IS_ERR(p))
                         break;
                 error = m->op->show(m, p);
-                if (error)
+                if (error < 0)
                         break;
+                if (unlikely(error)) {
+                        error = 0;
+                        m->count = 0;
+                }
                 if (m->count == m->size)
                         goto Eoverflow;
                 if (pos + m->count > offset) {
@@ -239,7 +247,7 @@ Eoverflow:
 loff_t seq_lseek(struct file *file, loff_t offset, int origin)
 {
         struct seq_file *m = (struct seq_file *)file->private_data;
-        long long retval = -EINVAL;
+        loff_t retval = -EINVAL;
 
         mutex_lock(&m->lock);
         m->version = file->f_version;
@@ -342,28 +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;
                         }
                 }
         }
@@ -372,6 +392,57 @@ int seq_path(struct seq_file *m, struct path *path, char *esc)
 }
 EXPORT_SYMBOL(seq_path);
 
+/*
+ * Same as seq_path, but relative to supplied root.
+ *
+ * root may be changed, see __d_path().
+ */
+int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
+                  char *esc)
+{
+        int err = -ENAMETOOLONG;
+        if (m->count < m->size) {
+                char *s = m->buf + m->count;
+                char *p;
+
+                spin_lock(&dcache_lock);
+                p = __d_path(path, root, s, m->size - m->count);
+                spin_unlock(&dcache_lock);
+                err = PTR_ERR(p);
+                if (!IS_ERR(p)) {
+                        s = mangle_path(s, p, esc);
+                        if (s) {
+                                p = m->buf + m->count;
+                                m->count = s - m->buf;
+                                return 0;
+                        }
+                }
+        }
+        m->count = m->size;
+        return err;
+}
+
+/*
+ * 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);