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authorLinus Torvalds <torvalds@linux-foundation.org>2012-11-29 12:27:00 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-11-29 12:38:44 -0800
commitab73857e354ab9e317613cba7db714e2c12c6547 (patch)
treede5b6fec7caec530f0dd72c9394a1a7d0b6f9878 /fs/direct-io.c
parent1e8b33328a5407b447ff80953655a47014a6dcb9 (diff)
downloadvexpress-lsk-ab73857e354ab9e317613cba7db714e2c12c6547.tar.gz
direct-io: don't read inode->i_blkbits multiple times
Since directio can work on a raw block device, and the block size of the device can change under it, we need to do the same thing that fs/buffer.c now does: read the block size a single time, using ACCESS_ONCE(). Reading it multiple times can get different results, which will then confuse the code because it actually encodes the i_blksize in relationship to the underlying logical blocksize. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/direct-io.c')
-rw-r--r--fs/direct-io.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c
index f86c720dba0..cf5b44b10c6 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -540,6 +540,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
sector_t fs_endblk; /* Into file, in filesystem-sized blocks */
unsigned long fs_count; /* Number of filesystem-sized blocks */
int create;
+ unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor;
/*
* If there was a memory error and we've overwritten all the
@@ -554,7 +555,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
fs_count = fs_endblk - fs_startblk + 1;
map_bh->b_state = 0;
- map_bh->b_size = fs_count << dio->inode->i_blkbits;
+ map_bh->b_size = fs_count << i_blkbits;
/*
* For writes inside i_size on a DIO_SKIP_HOLES filesystem we
@@ -1053,7 +1054,8 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
int seg;
size_t size;
unsigned long addr;
- unsigned blkbits = inode->i_blkbits;
+ unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits);
+ unsigned blkbits = i_blkbits;
unsigned blocksize_mask = (1 << blkbits) - 1;
ssize_t retval = -EINVAL;
loff_t end = offset;
@@ -1149,7 +1151,7 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
dio->inode = inode;
dio->rw = rw;
sdio.blkbits = blkbits;
- sdio.blkfactor = inode->i_blkbits - blkbits;
+ sdio.blkfactor = i_blkbits - blkbits;
sdio.block_in_file = offset >> blkbits;
sdio.get_block = get_block;