1 files changed, 92 insertions, 22 deletions

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 4023d6be939b..0cbd0494b79e 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -6,13 +6,29 @@
  */
 
 #include <linux/fs.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 
 #include <asm/uaccess.h>
 #include <asm/page.h>
 
+
+/*
+ * seq_files have a buffer which can may overflow. When this happens a larger
+ * buffer is reallocated and all the data will be printed again.
+ * The overflow state is true when m->count == m->size.
+ */
+static bool seq_overflow(struct seq_file *m)
+{
+	return m->count == m->size;
+}
+
+static void seq_set_overflow(struct seq_file *m)
+{
+	m->count = m->size;
+}
+
 /**
  *	seq_open -	initialize sequential file
  *	@file: file we initialize
@@ -92,7 +108,7 @@ static int traverse(struct seq_file *m, loff_t offset)
 			error = 0;
 			m->count = 0;
 		}
-		if (m->count == m->size)
+		if (seq_overflow(m))
 			goto Eoverflow;
 		if (pos + m->count > offset) {
 			m->from = offset - pos;
@@ -140,9 +156,21 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
 
 	mutex_lock(&m->lock);
 
+	/*
+	 * 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
+	 * pass the file->f_version to those methods.
+	 *
+	 * seq_file->version is just copy of f_version, and seq_file
+	 * methods can treat it simply as file version.
+	 * It is copied in first and copied out after all operations.
+	 * It is convenient to have it as  part of structure to avoid the
+	 * need of passing another argument to all the seq_file methods.
+	 */
+	m->version = file->f_version;
+
 	/* 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) {
@@ -152,21 +180,11 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
 			m->index = 0;
 			m->count = 0;
 			goto Done;
+		} else {
+			m->read_pos = *ppos;
 		}
 	}
 
-	/*
-	 * 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
-	 * pass the file->f_version to those methods.
-	 *
-	 * seq_file->version is just copy of f_version, and seq_file
-	 * methods can treat it simply as file version.
-	 * It is copied in first and copied out after all operations.
-	 * It is convenient to have it as  part of structure to avoid the
-	 * need of passing another argument to all the seq_file methods.
-	 */
-	m->version = file->f_version;
 	/* grab buffer if we didn't have one */
 	if (!m->buf) {
 		m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
@@ -232,7 +250,7 @@ Fill:
 			break;
 		}
 		err = m->op->show(m, p);
-		if (m->count == m->size || err) {
+		if (seq_overflow(m) || err) {
 			m->count = offs;
 			if (likely(err <= 0))
 				break;
@@ -359,7 +377,7 @@ int seq_escape(struct seq_file *m, const char *s, const char *esc)
 			*p++ = '0' + (c & 07);
 			continue;
 		}
-		m->count = m->size;
+		seq_set_overflow(m);
 		return -1;
         }
 	m->count = p - m->buf;
@@ -381,7 +399,7 @@ int seq_printf(struct seq_file *m, const char *f, ...)
 			return 0;
 		}
 	}
-	m->count = m->size;
+	seq_set_overflow(m);
 	return -1;
 }
 EXPORT_SYMBOL(seq_printf);
@@ -510,7 +528,7 @@ int seq_bitmap(struct seq_file *m, const unsigned long *bits,
 			return 0;
 		}
 	}
-	m->count = m->size;
+	seq_set_overflow(m);
 	return -1;
 }
 EXPORT_SYMBOL(seq_bitmap);
@@ -526,7 +544,7 @@ int seq_bitmap_list(struct seq_file *m, const unsigned long *bits,
 			return 0;
 		}
 	}
-	m->count = m->size;
+	seq_set_overflow(m);
 	return -1;
 }
 EXPORT_SYMBOL(seq_bitmap_list);
@@ -637,11 +655,63 @@ int seq_puts(struct seq_file *m, const char *s)
 		m->count += len;
 		return 0;
 	}
-	m->count = m->size;
+	seq_set_overflow(m);
 	return -1;
 }
 EXPORT_SYMBOL(seq_puts);
 
+/*
+ * A helper routine for putting decimal numbers without rich format of printf().
+ * only 'unsigned long long' is supported.
+ * This routine will put one byte delimiter + number into seq_file.
+ * This routine is very quick when you show lots of numbers.
+ * In usual cases, it will be better to use seq_printf(). It's easier to read.
+ */
+int seq_put_decimal_ull(struct seq_file *m, char delimiter,
+			unsigned long long num)
+{
+	int len;
+
+	if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
+		goto overflow;
+
+	if (delimiter)
+		m->buf[m->count++] = delimiter;
+
+	if (num < 10) {
+		m->buf[m->count++] = num + '0';
+		return 0;
+	}
+
+	len = num_to_str(m->buf + m->count, m->size - m->count, num);
+	if (!len)
+		goto overflow;
+	m->count += len;
+	return 0;
+overflow:
+	seq_set_overflow(m);
+	return -1;
+}
+EXPORT_SYMBOL(seq_put_decimal_ull);
+
+int seq_put_decimal_ll(struct seq_file *m, char delimiter,
+			long long num)
+{
+	if (num < 0) {
+		if (m->count + 3 >= m->size) {
+			seq_set_overflow(m);
+			return -1;
+		}
+		if (delimiter)
+			m->buf[m->count++] = delimiter;
+		num = -num;
+		delimiter = '-';
+	}
+	return seq_put_decimal_ull(m, delimiter, num);
+
+}
+EXPORT_SYMBOL(seq_put_decimal_ll);
+
 /**
  * seq_write - write arbitrary data to buffer
  * @seq: seq_file identifying the buffer to which data should be written
@@ -657,7 +727,7 @@ int seq_write(struct seq_file *seq, const void *data, size_t len)
 		seq->count += len;
 		return 0;
 	}
-	seq->count = seq->size;
+	seq_set_overflow(seq);
 	return -1;
 }
 EXPORT_SYMBOL(seq_write);