seq_file: add seq_set_overflow(), seq_overflow()
It is undocumented but a seq_file's overflow state is indicated by
m->count == m->size. Add seq_set_overflow() and seq_overflow() to
set/check overflow status explicitly.
Based on an idea from Eric Dumazet.
[akpm@linux-foundation.org: tweak code comment]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 55c293f..46cfb06 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -13,6 +13,22 @@
#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 @@
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;
@@ -234,7 +250,7 @@
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;
@@ -361,7 +377,7 @@
*p++ = '0' + (c & 07);
continue;
}
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
m->count = p - m->buf;
@@ -383,7 +399,7 @@
return 0;
}
}
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
EXPORT_SYMBOL(seq_printf);
@@ -512,7 +528,7 @@
return 0;
}
}
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
EXPORT_SYMBOL(seq_bitmap);
@@ -528,7 +544,7 @@
return 0;
}
}
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
EXPORT_SYMBOL(seq_bitmap_list);
@@ -639,7 +655,7 @@
m->count += len;
return 0;
}
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
EXPORT_SYMBOL(seq_puts);
@@ -673,7 +689,7 @@
m->count += len;
return 0;
overflow:
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
EXPORT_SYMBOL(seq_put_decimal_ull);
@@ -683,7 +699,7 @@
{
if (num < 0) {
if (m->count + 3 >= m->size) {
- m->count = m->size;
+ seq_set_overflow(m);
return -1;
}
if (delimiter)
@@ -711,7 +727,7 @@
seq->count += len;
return 0;
}
- seq->count = seq->size;
+ seq_set_overflow(seq);
return -1;
}
EXPORT_SYMBOL(seq_write);