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Btrfs: allow unaligned DIO 

In order to support DIO that isn't aligned to the filesystem blocksize,
we fall back to buffered for any unaligned DIOs.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
wifi-calibration
Chris Mason 2010-05-26 21:33:37 -04:00
parent 933b585f70
commit 5a5f79b570
1 changed files with 35 additions and 3 deletions
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38
fs/btrfs/inode.c
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@ -5722,6 +5722,32 @@ free_ordered:
bio_endio(bio, ret);
}
static ssize_t check_direct_IO(struct btrfs_root *root, int rw, struct kiocb *iocb,
const struct iovec *iov, loff_t offset,
unsigned long nr_segs)
{
int seg;
size_t size;
unsigned long addr;
unsigned blocksize_mask = root->sectorsize - 1;
ssize_t retval = -EINVAL;
loff_t end = offset;
if (offset & blocksize_mask)
goto out;
/* Check the memory alignment. Blocks cannot straddle pages */
for (seg = 0; seg < nr_segs; seg++) {
addr = (unsigned long)iov[seg].iov_base;
size = iov[seg].iov_len;
end += size;
if ((addr & blocksize_mask) || (size & blocksize_mask))
goto out;
}
retval = 0;
out:
return retval;
}
static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
const struct iovec *iov, loff_t offset,
unsigned long nr_segs)
@ -5736,6 +5762,11 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
int write_bits = 0;
size_t count = iov_length(iov, nr_segs);
if (check_direct_IO(BTRFS_I(inode)->root, rw, iocb, iov,
offset, nr_segs)) {
return 0;
}
lockstart = offset;
lockend = offset + count - 1;
@ -5784,9 +5815,10 @@ static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb,
free_extent_state(cached_state);
cached_state = NULL;
ret = __blockdev_direct_IO(rw, iocb, inode, NULL, iov, offset, nr_segs,
btrfs_get_blocks_direct, NULL,
btrfs_submit_direct, 0);
ret = __blockdev_direct_IO(rw, iocb, inode,
BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev,
iov, offset, nr_segs, btrfs_get_blocks_direct, NULL,
btrfs_submit_direct, 0);
if (ret < 0 && ret != -EIOCBQUEUED) {
clear_extent_bit(&BTRFS_I(inode)->io_tree, offset,