[patch 099/108] dm: use i_size_read

Greg KH
2009-07-01T01:16:03Z

[-- Attachment #1: dm-use-i_size_read.patch --]
[-- Type: text/plain, Size: 2188 bytes --]

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

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

From: Mikulas Patocka <mpatocka@redhat.com>

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@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
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;