gfs2: Fix extended attribute readahead optimization

Commit 39b0555f didn't check for a failing bio_add_page in
gfs2_submit_bhs. This could cause I/O requests to get lost, and the
affected buffer heads to stay locked forever.  Fix that by submitting
the current bio and allocating another one when bio_add_page fails.  (It
is guaranteed that we can at least add one page to a bio.)

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

1 files changed, 19 insertions, 16 deletions

diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index 950b8be68e41..373639a59782 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -216,23 +216,26 @@ static void gfs2_meta_read_endio(struct bio *bio)
 static void gfs2_submit_bhs(int op, int op_flags, struct buffer_head *bhs[],
                             int num)
 {
-        struct buffer_head *bh = bhs[0];
-        struct bio *bio;
-        int i;
-
-        if (!num)
-                return;
-
-        bio = bio_alloc(GFP_NOIO, num);
-        bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
-        bio->bi_bdev = bh->b_bdev;
-        for (i = 0; i < num; i++) {
-                bh = bhs[i];
-                bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
+        while (num > 0) {
+                struct buffer_head *bh = *bhs;
+                struct bio *bio;
+
+                bio = bio_alloc(GFP_NOIO, num);
+                bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
+                bio->bi_bdev = bh->b_bdev;
+                while (num > 0) {
+                        bh = *bhs;
+                        if (!bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh))) {
+                                BUG_ON(bio->bi_iter.bi_size == 0);
+                                break;
+                        }
+                        bhs++;
+                        num--;
+                }
+                bio->bi_end_io = gfs2_meta_read_endio;
+                bio_set_op_attrs(bio, op, op_flags);
+                submit_bio(bio);
         }
-        bio->bi_end_io = gfs2_meta_read_endio;
-        bio_set_op_attrs(bio, op, op_flags);
-        submit_bio(bio);
 }
 
 /**