X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=fs%2Fseq_file.c;h=e1f437be6c3c85c288ca3d3b76c15bf409da0f4c;hb=4dc6ec00f6347b72312fa41dfc587d5302b05544;hp=11c85fec6b4f60b25a83480adb77fa62f098d015;hpb=85dd030edb174376ef43bc95e5fae4755af1ec98;p=safe%2Fjmp%2Flinux-2.6

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 11c85fe..e1f437b 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -48,12 +48,78 @@ int seq_open(struct file *file, const struct seq_operations *op)
 	 */
 	file->f_version = 0;
 
-	/* SEQ files support lseek, but not pread/pwrite */
-	file->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
+	/*
+	 * seq_files support lseek() and pread().  They do not implement
+	 * write() at all, but we clear FMODE_PWRITE here for historical
+	 * reasons.
+	 *
+	 * If a client of seq_files a) implements file.write() and b) wishes to
+	 * support pwrite() then that client will need to implement its own
+	 * file.open() which calls seq_open() and then sets FMODE_PWRITE.
+	 */
+	file->f_mode &= ~FMODE_PWRITE;
 	return 0;
 }
 EXPORT_SYMBOL(seq_open);
 
+static int traverse(struct seq_file *m, loff_t offset)
+{
+	loff_t pos = 0, index;
+	int error = 0;
+	void *p;
+
+	m->version = 0;
+	index = 0;
+	m->count = m->from = 0;
+	if (!offset) {
+		m->index = index;
+		return 0;
+	}
+	if (!m->buf) {
+		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
+		if (!m->buf)
+			return -ENOMEM;
+	}
+	p = m->op->start(m, &index);
+	while (p) {
+		error = PTR_ERR(p);
+		if (IS_ERR(p))
+			break;
+		error = m->op->show(m, p);
+		if (error < 0)
+			break;
+		if (unlikely(error)) {
+			error = 0;
+			m->count = 0;
+		}
+		if (m->count == m->size)
+			goto Eoverflow;
+		if (pos + m->count > offset) {
+			m->from = offset - pos;
+			m->count -= m->from;
+			m->index = index;
+			break;
+		}
+		pos += m->count;
+		m->count = 0;
+		if (pos == offset) {
+			index++;
+			m->index = index;
+			break;
+		}
+		p = m->op->next(m, p, &index);
+	}
+	m->op->stop(m, p);
+	m->index = index;
+	return error;
+
+Eoverflow:
+	m->op->stop(m, p);
+	kfree(m->buf);
+	m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
+	return !m->buf ? -ENOMEM : -EAGAIN;
+}
+
 /**
  *	seq_read -	->read() method for sequential files.
  *	@file: the file to read from
@@ -73,6 +139,22 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
 	int err = 0;
 
 	mutex_lock(&m->lock);
+
+	/* Don't assume *ppos is where we left it */
+	if (unlikely(*ppos != m->read_pos)) {
+		m->read_pos = *ppos;
+		while ((err = traverse(m, *ppos)) == -EAGAIN)
+			;
+		if (err) {
+			/* With prejudice... */
+			m->read_pos = 0;
+			m->version = 0;
+			m->index = 0;
+			m->count = 0;
+			goto Done;
+		}
+	}
+
 	/*
 	 * seq_file->op->..m_start/m_stop/m_next may do special actions
 	 * or optimisations based on the file->f_version, so we want to
@@ -172,8 +254,10 @@ Fill:
 Done:
 	if (!copied)
 		copied = err;
-	else
+	else {
 		*ppos += copied;
+		m->read_pos += copied;
+	}
 	file->f_version = m->version;
 	mutex_unlock(&m->lock);
 	return copied;
@@ -186,63 +270,6 @@ Efault:
 }
 EXPORT_SYMBOL(seq_read);
 
-static int traverse(struct seq_file *m, loff_t offset)
-{
-	loff_t pos = 0, index;
-	int error = 0;
-	void *p;
-
-	m->version = 0;
-	index = 0;
-	m->count = m->from = 0;
-	if (!offset) {
-		m->index = index;
-		return 0;
-	}
-	if (!m->buf) {
-		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
-		if (!m->buf)
-			return -ENOMEM;
-	}
-	p = m->op->start(m, &index);
-	while (p) {
-		error = PTR_ERR(p);
-		if (IS_ERR(p))
-			break;
-		error = m->op->show(m, p);
-		if (error < 0)
-			break;
-		if (unlikely(error)) {
-			error = 0;
-			m->count = 0;
-		}
-		if (m->count == m->size)
-			goto Eoverflow;
-		if (pos + m->count > offset) {
-			m->from = offset - pos;
-			m->count -= m->from;
-			m->index = index;
-			break;
-		}
-		pos += m->count;
-		m->count = 0;
-		if (pos == offset) {
-			index++;
-			m->index = index;
-			break;
-		}
-		p = m->op->next(m, p, &index);
-	}
-	m->op->stop(m, p);
-	return error;
-
-Eoverflow:
-	m->op->stop(m, p);
-	kfree(m->buf);
-	m->buf = kmalloc(m->size <<= 1, GFP_KERNEL);
-	return !m->buf ? -ENOMEM : -EAGAIN;
-}
-
 /**
  *	seq_lseek -	->llseek() method for sequential files.
  *	@file: the file in question
@@ -265,16 +292,18 @@ loff_t seq_lseek(struct file *file, loff_t offset, int origin)
 			if (offset < 0)
 				break;
 			retval = offset;
-			if (offset != file->f_pos) {
+			if (offset != m->read_pos) {
 				while ((retval=traverse(m, offset)) == -EAGAIN)
 					;
 				if (retval) {
 					/* with extreme prejudice... */
 					file->f_pos = 0;
+					m->read_pos = 0;
 					m->version = 0;
 					m->index = 0;
 					m->count = 0;
 				} else {
+					m->read_pos = offset;
 					retval = file->f_pos = offset;
 				}
 			}
@@ -357,7 +386,18 @@ int seq_printf(struct seq_file *m, const char *f, ...)
 }
 EXPORT_SYMBOL(seq_printf);
 
-static char *mangle_path(char *s, char *p, char *esc)
+/**
+ *	mangle_path -	mangle and copy path to buffer beginning
+ *	@s: buffer start
+ *	@p: beginning of path in above buffer
+ *	@esc: set of characters that need escaping
+ *
+ *      Copy the path from @p to @s, replacing each occurrence of character from
+ *      @esc with usual octal escape.
+ *      Returns pointer past last written character in @s, or NULL in case of
+ *      failure.
+ */
+char *mangle_path(char *s, char *p, char *esc)
 {
 	while (s <= p) {
 		char c = *p++;
@@ -376,26 +416,34 @@ static char *mangle_path(char *s, char *p, char *esc)
 	}
 	return NULL;
 }
+EXPORT_SYMBOL(mangle_path);
 
-/*
- * return the absolute path of 'dentry' residing in mount 'mnt'.
+/**
+ * seq_path - seq_file interface to print a pathname
+ * @m: the seq_file handle
+ * @path: the struct path to print
+ * @esc: set of characters to escape in the output
+ *
+ * return the absolute path of 'path', as represented by the
+ * dentry / mnt pair in the path parameter.
  */
 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);
+	char *buf;
+	size_t size = seq_get_buf(m, &buf);
+	int res = -1;
+
+	if (size) {
+		char *p = d_path(path, buf, size);
 		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;
-			}
+			char *end = mangle_path(buf, p, esc);
+			if (end)
+				res = end - buf;
 		}
 	}
-	m->count = m->size;
-	return -1;
+	seq_commit(m, res);
+
+	return res;
 }
 EXPORT_SYMBOL(seq_path);
 
@@ -407,26 +455,28 @@ EXPORT_SYMBOL(seq_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 *buf;
+	size_t size = seq_get_buf(m, &buf);
+	int res = -ENAMETOOLONG;
+
+	if (size) {
 		char *p;
 
 		spin_lock(&dcache_lock);
-		p = __d_path(path, root, s, m->size - m->count);
+		p = __d_path(path, root, buf, size);
 		spin_unlock(&dcache_lock);
-		err = PTR_ERR(p);
+		res = 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;
-			}
+			char *end = mangle_path(buf, p, esc);
+			if (end)
+				res = end - buf;
+			else
+				res = -ENAMETOOLONG;
 		}
 	}
-	m->count = m->size;
-	return err;
+	seq_commit(m, res);
+
+	return res < 0 ? res : 0;
 }
 
 /*
@@ -434,23 +484,25 @@ int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
  */
 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);
+	char *buf;
+	size_t size = seq_get_buf(m, &buf);
+	int res = -1;
+
+	if (size) {
+		char *p = dentry_path(dentry, buf, size);
 		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;
-			}
+			char *end = mangle_path(buf, p, esc);
+			if (end)
+				res = end - buf;
 		}
 	}
-	m->count = m->size;
-	return -1;
+	seq_commit(m, res);
+
+	return res;
 }
 
-int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits)
+int seq_bitmap(struct seq_file *m, const unsigned long *bits,
+				   unsigned int nr_bits)
 {
 	if (m->count < m->size) {
 		int len = bitmap_scnprintf(m->buf + m->count,
@@ -465,6 +517,22 @@ int seq_bitmap(struct seq_file *m, unsigned long *bits, unsigned int nr_bits)
 }
 EXPORT_SYMBOL(seq_bitmap);
 
+int seq_bitmap_list(struct seq_file *m, const unsigned long *bits,
+		unsigned int nr_bits)
+{
+	if (m->count < m->size) {
+		int len = bitmap_scnlistprintf(m->buf + m->count,
+				m->size - m->count, bits, nr_bits);
+		if (m->count + len < m->size) {
+			m->count += len;
+			return 0;
+		}
+	}
+	m->count = m->size;
+	return -1;
+}
+EXPORT_SYMBOL(seq_bitmap_list);
+
 static void *single_start(struct seq_file *p, loff_t *pos)
 {
 	return NULL + (*pos == 0);
@@ -576,6 +644,26 @@ int seq_puts(struct seq_file *m, const char *s)
 }
 EXPORT_SYMBOL(seq_puts);
 
+/**
+ * seq_write - write arbitrary data to buffer
+ * @seq: seq_file identifying the buffer to which data should be written
+ * @data: data address
+ * @len: number of bytes
+ *
+ * Return 0 on success, non-zero otherwise.
+ */
+int seq_write(struct seq_file *seq, const void *data, size_t len)
+{
+	if (seq->count + len < seq->size) {
+		memcpy(seq->buf + seq->count, data, len);
+		seq->count += len;
+		return 0;
+	}
+	seq->count = seq->size;
+	return -1;
+}
+EXPORT_SYMBOL(seq_write);
+
 struct list_head *seq_list_start(struct list_head *head, loff_t pos)
 {
 	struct list_head *lh;
@@ -586,7 +674,6 @@ struct list_head *seq_list_start(struct list_head *head, loff_t pos)
 
 	return NULL;
 }
-
 EXPORT_SYMBOL(seq_list_start);
 
 struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
@@ -596,7 +683,6 @@ struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
 
 	return seq_list_start(head, pos - 1);
 }
-
 EXPORT_SYMBOL(seq_list_start_head);
 
 struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
@@ -607,5 +693,131 @@ struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
 	++*ppos;
 	return lh == head ? NULL : lh;
 }
-
 EXPORT_SYMBOL(seq_list_next);
+
+/**
+ * seq_hlist_start - start an iteration of a hlist
+ * @head: the head of the hlist
+ * @pos:  the start position of the sequence
+ *
+ * Called at seq_file->op->start().
+ */
+struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
+{
+	struct hlist_node *node;
+
+	hlist_for_each(node, head)
+		if (pos-- == 0)
+			return node;
+	return NULL;
+}
+EXPORT_SYMBOL(seq_hlist_start);
+
+/**
+ * seq_hlist_start_head - start an iteration of a hlist
+ * @head: the head of the hlist
+ * @pos:  the start position of the sequence
+ *
+ * Called at seq_file->op->start(). Call this function if you want to
+ * print a header at the top of the output.
+ */
+struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
+{
+	if (!pos)
+		return SEQ_START_TOKEN;
+
+	return seq_hlist_start(head, pos - 1);
+}
+EXPORT_SYMBOL(seq_hlist_start_head);
+
+/**
+ * seq_hlist_next - move to the next position of the hlist
+ * @v:    the current iterator
+ * @head: the head of the hlist
+ * @ppos: the current position
+ *
+ * Called at seq_file->op->next().
+ */
+struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
+				  loff_t *ppos)
+{
+	struct hlist_node *node = v;
+
+	++*ppos;
+	if (v == SEQ_START_TOKEN)
+		return head->first;
+	else
+		return node->next;
+}
+EXPORT_SYMBOL(seq_hlist_next);
+
+/**
+ * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
+ * @head: the head of the hlist
+ * @pos:  the start position of the sequence
+ *
+ * Called at seq_file->op->start().
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as hlist_add_head_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
+				       loff_t pos)
+{
+	struct hlist_node *node;
+
+	__hlist_for_each_rcu(node, head)
+		if (pos-- == 0)
+			return node;
+	return NULL;
+}
+EXPORT_SYMBOL(seq_hlist_start_rcu);
+
+/**
+ * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
+ * @head: the head of the hlist
+ * @pos:  the start position of the sequence
+ *
+ * Called at seq_file->op->start(). Call this function if you want to
+ * print a header at the top of the output.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as hlist_add_head_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
+					    loff_t pos)
+{
+	if (!pos)
+		return SEQ_START_TOKEN;
+
+	return seq_hlist_start_rcu(head, pos - 1);
+}
+EXPORT_SYMBOL(seq_hlist_start_head_rcu);
+
+/**
+ * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
+ * @v:    the current iterator
+ * @head: the head of the hlist
+ * @ppos: the current position
+ *
+ * Called at seq_file->op->next().
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as hlist_add_head_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ */
+struct hlist_node *seq_hlist_next_rcu(void *v,
+				      struct hlist_head *head,
+				      loff_t *ppos)
+{
+	struct hlist_node *node = v;
+
+	++*ppos;
+	if (v == SEQ_START_TOKEN)
+		return rcu_dereference(head->first);
+	else
+		return rcu_dereference(node->next);
+}
+EXPORT_SYMBOL(seq_hlist_next_rcu);