[PATCH] fs: guard_bio_eod() needs to consider partitions

[Greg Edwards]

guard_bio_eod() needs to look at the partition capacity, not just the
capacity of the whole device, when determining if truncation is
necessary.

[   60.268688] attempt to access beyond end of device
[   60.268690] unknown-block(9,1): rw=0, want=67103509, limit=67103506
[   60.268693] buffer_io_error: 2 callbacks suppressed
[   60.268696] Buffer I/O error on dev md1p7, logical block 4524305, async page 
read

Fixes: 74d46992e0d9 ("block: replace bi_bdev with a gendisk pointer and 
partitions index")
Signed-off-by: Greg Edwards <gedwa...@ddn.com>
---
 fs/buffer.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 170df856bdb9..989d3b085efe 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3055,8 +3055,15 @@ void guard_bio_eod(int op, struct bio *bio)
        sector_t maxsector;
        struct bio_vec *bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
        unsigned truncated_bytes;
+       struct hd_struct *part;
+
+       part = disk_get_part(bio->bi_disk, bio->bi_partno);
+       if (part)
+               maxsector = part_nr_sects_read(part);
+       else
+               maxsector = get_capacity(bio->bi_disk);
+       disk_put_part(part);
 
-       maxsector = get_capacity(bio->bi_disk);
        if (!maxsector)
                return;
 
-- 
2.13.6