[patch 099/108] dm: use i_size_read

[Greg KH]

2.6.30-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Mikulas Patocka <mpatocka@xxxxxxxxxx>

commit 5657e8fa45cf230df278040c420fb80e06309d8f upstream.

Use i_size_read() instead of reading i_size.

If someone changes the size of the device simultaneously, i_size_read
is guaranteed to return a valid value (either the old one or the new one).

i_size can return some intermediate invalid value (on 32-bit computers
with 64-bit i_size, the reads to both halves of i_size can be interleaved
with updates to i_size, resulting in garbage being returned).

Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Alasdair G Kergon <agk@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/md/dm-exception-store.h |    2 +-
 drivers/md/dm-log.c             |    2 +-
 drivers/md/dm-table.c           |    3 ++-
 3 files changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -156,7 +156,7 @@ static inline void dm_consecutive_chunk_
  */
 static inline sector_t get_dev_size(struct block_device *bdev)
 {
-	return bdev->bd_inode->i_size >> SECTOR_SHIFT;
+	return i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
 }
 
 static inline chunk_t sector_to_chunk(struct dm_exception_store *store,
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -415,7 +415,7 @@ static int create_log_context(struct dm_
 		buf_size = dm_round_up((LOG_OFFSET << SECTOR_SHIFT) +
 				       bitset_size, ti->limits.hardsect_size);
 
-		if (buf_size > dev->bdev->bd_inode->i_size) {
+		if (buf_size > i_size_read(dev->bdev->bd_inode)) {
 			DMWARN("log device %s too small: need %llu bytes",
 				dev->name, (unsigned long long)buf_size);
 			kfree(lc);
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -387,7 +387,8 @@ static void close_dev(struct dm_dev_inte
 static int check_device_area(struct dm_dev_internal *dd, sector_t start,
 			     sector_t len)
 {
-	sector_t dev_size = dd->dm_dev.bdev->bd_inode->i_size >> SECTOR_SHIFT;
+	sector_t dev_size = i_size_read(dd->dm_dev.bdev->bd_inode) >>
+			    SECTOR_SHIFT;
 
 	if (!dev_size)
 		return 1;


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/