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new primitive: iov_iter_alignment()

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returns the value aligned as badly as the worst remaining segment
in iov_iter is.  Use instead of open-coded equivalents.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2014-03-05 13:50:45 -05:00
parent 26978b8b4d
commit 886a391150
4 changed files with 34 additions and 27 deletions
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27
fs/direct-io.c
View file

@ -1112,19 +1112,18 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
dio_submit_t submit_io, int flags)
{
int seg;
size_t size;
unsigned long addr;
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;
loff_t end = offset + iov_iter_count(iter);
struct dio *dio;
struct dio_submit sdio = { 0, };
unsigned long user_addr;
size_t bytes;
struct buffer_head map_bh = { 0, };
struct blk_plug plug;
unsigned long align = offset | iov_iter_alignment(iter);
if (rw & WRITE)
rw = WRITE_ODIRECT;
@ -1134,32 +1133,16 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
* the early prefetch in the caller enough time.
*/
if (offset & blocksize_mask) {
if (align & blocksize_mask) {
if (bdev)
blkbits = blksize_bits(bdev_logical_block_size(bdev));
blocksize_mask = (1 << blkbits) - 1;
if (offset & blocksize_mask)
if (align & blocksize_mask)
goto out;
}
/* Check the memory alignment. Blocks cannot straddle pages */
for (seg = 0; seg < iter->nr_segs; seg++) {
addr = (unsigned long)iter->iov[seg].iov_base;
size = iter->iov[seg].iov_len;
end += size;
if (unlikely((addr & blocksize_mask) ||
(size & blocksize_mask))) {
if (bdev)
blkbits = blksize_bits(
bdev_logical_block_size(bdev));
blocksize_mask = (1 << blkbits) - 1;
if ((addr & blocksize_mask) || (size & blocksize_mask))
goto out;
}
}
/* watch out for a 0 len io from a tricksy fs */
if (rw == READ && end == offset)
if (rw == READ && !iov_iter_count(iter))
return 0;
dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);