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SubjectRe: [PATCH 3/7] dax: remove buffer_size_valid()
On Mon 15-08-16 13:09:14, Ross Zwisler wrote:
> Now that all our supported filesystems (ext2, ext4 and XFS) all properly
> set bh.b_size when we call get_block() for a hole, rely on that value and
> remove the buffer_size_valid() sanity check.
>
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> fs/dax.c | 22 +---------------------
> 1 file changed, 1 insertion(+), 21 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 993dc6f..8030f93 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -121,19 +121,6 @@ static bool buffer_written(struct buffer_head *bh)
> return buffer_mapped(bh) && !buffer_unwritten(bh);
> }
>
> -/*
> - * When ext4 encounters a hole, it returns without modifying the buffer_head
> - * which means that we can't trust b_size. To cope with this, we set b_state
> - * to 0 before calling get_block and, if any bit is set, we know we can trust
> - * b_size. Unfortunate, really, since ext4 knows precisely how long a hole is
> - * and would save us time calling get_block repeatedly.
> - */
> -static bool buffer_size_valid(struct buffer_head *bh)
> -{
> - return bh->b_state != 0;
> -}
> -
> -
> static sector_t to_sector(const struct buffer_head *bh,
> const struct inode *inode)
> {
> @@ -175,8 +162,6 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
> rc = get_block(inode, block, bh, rw == WRITE);
> if (rc)
> break;
> - if (!buffer_size_valid(bh))
> - bh->b_size = 1 << blkbits;
> bh_max = pos - first + bh->b_size;
> bdev = bh->b_bdev;
> /*
> @@ -1010,12 +995,7 @@ int dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
>
> bdev = bh.b_bdev;
>
> - /*
> - * If the filesystem isn't willing to tell us the length of a hole,
> - * just fall back to PTEs. Calling get_block 512 times in a loop
> - * would be silly.
> - */
> - if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) {
> + if (bh.b_size < PMD_SIZE) {
> dax_pmd_dbg(&bh, address, "allocated block too small");
> return VM_FAULT_FALLBACK;
> }
> --
> 2.9.0
>
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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