GFS2: Size seq_file buffer more carefully

This places a limit on the buffer size for archs with larger
PAGE_SIZE.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 4d5d63d9d2c0..1ed81f40da0d 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1977,6 +1977,8 @@ static const struct seq_operations gfs2_sbstats_seq_ops = {
         .show  = gfs2_sbstats_seq_show,
 };
 
+#define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
+
 static int gfs2_glocks_open(struct inode *inode, struct file *file)
 {
         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
@@ -1985,9 +1987,9 @@ static int gfs2_glocks_open(struct inode *inode, struct file *file)
                 struct seq_file *seq = file->private_data;
                 struct gfs2_glock_iter *gi = seq->private;
                 gi->sdp = inode->i_private;
-                seq->buf = kmalloc(8*PAGE_SIZE, GFP_KERNEL | __GFP_NOWARN);
+                seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
                 if (seq->buf)
-                        seq->size = 8*PAGE_SIZE;
+                        seq->size = GFS2_SEQ_GOODSIZE;
         }
         return ret;
 }
@@ -2000,9 +2002,9 @@ static int gfs2_glstats_open(struct inode *inode, struct file *file)
                 struct seq_file *seq = file->private_data;
                 struct gfs2_glock_iter *gi = seq->private;
                 gi->sdp = inode->i_private;
-                seq->buf = kmalloc(8*PAGE_SIZE, GFP_KERNEL | __GFP_NOWARN);
+                seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
                 if (seq->buf)
-                        seq->size = 8*PAGE_SIZE;
+                        seq->size = GFS2_SEQ_GOODSIZE;
         }
         return ret;
 }