[PATCH 10/16] GFS2: Size seq_file buffer more carefully

[Steven Whitehouse]

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

Signed-off-by: Steven Whitehouse <swhiteho@xxxxxxxxxx>
Reported-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 4d5d63d..1ed81f4 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;
 }
-- 
1.7.4

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