CC to Dave.
Thanks,
-Jeff
On 11/22/2011 04:19 PM, Jeff Liu wrote:
> Hello,
>
> This is the V2 attempt to add SEEK_DATA/SEEK_HOLE to XFS.
>
> Changes:
> ========
> 1. Merge xfs_find_desired_extent() and xfs_seek_data_hole() into xfs_seek_extent(), and place it at xfs_file.c.
> 2. Using two different routines xfs_seek_data()/xfs_seek_hole() to handle SEEK_DATA/SEEK_HOLE requests respectively.
> 3. Remove some worthless result checking code from xfs_file_llseek().
> 4. s/xfs_mount_t/struct xfs_mount/g.
>
> Tests:
> ======
> In addition to the seek_test.c I have used previously, I have also done a large sparse file copy tests, it works to me.
>
> Hope I have not made obvious stupid mistakes this time. :-P.
> Any comments are appreciated!
>
>
> Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
>
> ---
> fs/xfs/xfs_file.c | 188 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 187 insertions(+), 1 deletions(-)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 753ed9b..bb2be00 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1141,8 +1141,194 @@ xfs_vm_page_mkwrite(
> return block_page_mkwrite(vma, vmf, xfs_get_blocks);
> }
>
> +STATIC int
> +xfs_seek_data(
> + struct xfs_inode *ip,
> + loff_t *start)
> +{
> + struct xfs_mount *mp = ip->i_mount;
> + struct xfs_ifork *ifp;
> + xfs_fileoff_t fsbno;
> + xfs_filblks_t len;
> + loff_t startoff = *start;
> + int error = 0;
> +
> + fsbno = XFS_B_TO_FSBT(mp, *start);
> + ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
> + len = XFS_B_TO_FSB(mp, ip->i_size);
> +
> + for (;;) {
> + struct xfs_bmbt_irec map[2];
> + int nmap = 2;
> + loff_t seekoff;
> +
> + error = xfs_bmapi_read(ip, fsbno, len - fsbno, map, &nmap,
> + XFS_BMAPI_ENTIRE);
> + if (error)
> + break;
> +
> + /* No extents at given offset, must be beyond EOF */
> + if (!nmap) {
> + error = ENXIO;
> + break;
> + }
> +
> + seekoff = XFS_FSB_TO_B(mp, fsbno);
> +
> + /*
> + * Hole handling for unwritten extents landed in a hole.
> + * If the next extent is a data extent, then return the
> + * start of it, otherwise we need to move the start offset
> + * and map more blocks.
> + */
> + if (map[0].br_startblock == HOLESTARTBLOCK) {
> + if (map[1].br_startblock == HOLESTARTBLOCK) {
> + fsbno = map[1].br_startoff +
> + map[1].br_blockcount;
> + } else {
> + *start = max_t(loff_t, seekoff,
> + XFS_FSB_TO_B(mp, map[1].br_startoff));
> + break;
> + }
> + }
> +
> + /*
> + * Landed in an in-memory data extent or in an allocated
> + * extent.
> + */
> + if (map[0].br_startoff == DELAYSTARTBLOCK ||
> + map[0].br_state == XFS_EXT_NORM) {
> + *start = max_t(loff_t, seekoff,
> + XFS_FSB_TO_B(mp, map[0].br_startoff));
> + break;
> + }
> +
> + /* return ENXIO if beyond eof */
> + if (XFS_FSB_TO_B(mp, fsbno) > ip->i_size) {
> + error = ENXIO;
> + break;
> + }
> + }
> +
> + if (*start < startoff)
> + *start = startoff;
> +
> + return error;
> +}
> +
> +STATIC int
> +xfs_seek_hole(
> + struct xfs_inode *ip,
> + loff_t *start)
> +{
> + struct xfs_mount *mp = ip->i_mount;
> + int error = 0;
> + loff_t seekoff = *start;
> + loff_t holeoff;
> + xfs_fileoff_t fsbno;
> +
> + fsbno = XFS_B_TO_FSBT(mp, *start);
> + error = xfs_bmap_first_unused(NULL, ip, 1, &fsbno, XFS_DATA_FORK);
> + if (error)
> + return error;
> +
> + holeoff = XFS_FSB_TO_B(mp, fsbno);
> + if (holeoff <= seekoff)
> + *start = seekoff;
> + else
> + *start = min_t(loff_t, holeoff, ip->i_size);
> +
> + return error;
> +}
> +
> +STATIC int
> +xfs_seek_extent(
> + struct inode *inode,
> + loff_t *start,
> + u32 type)
> +{
> + struct xfs_inode *ip = XFS_I(inode);
> + struct xfs_mount *mp = ip->i_mount;
> + struct xfs_ifork *ifp;
> + int lock;
> + int error = 0;
> +
> + if (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS &&
> + ip->i_d.di_format != XFS_DINODE_FMT_BTREE &&
> + ip->i_d.di_format != XFS_DINODE_FMT_LOCAL)
> + return XFS_ERROR(EINVAL);
> +
> + lock = xfs_ilock_map_shared(ip);
> +
> + if (XFS_FORCED_SHUTDOWN(mp)) {
> + error = EIO;
> + goto out_lock;
> + }
> +
> + XFS_STATS_INC(xs_blk_mapr);
> + ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
> +
> + ASSERT(ifp->if_ext_max ==
> + XFS_IFORK_SIZE(ip, XFS_DATA_FORK) / (uint)sizeof(xfs_bmbt_rec_t));
> +
> + if (!(ifp->if_flags & XFS_IFEXTENTS)) {
> + error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
> + if (error)
> + goto out_lock;
> + }
> +
> + if (type == SEEK_HOLE)
> + error = xfs_seek_hole(ip, start);
> + else
> + error = xfs_seek_data(ip, start);
> +
> +out_lock:
> + xfs_iunlock_map_shared(ip, lock);
> +
> + if (error)
> + return -error;
> +
> + return 0;
> +}
> +
> +STATIC loff_t
> +xfs_file_llseek(
> + struct file *file,
> + loff_t offset,
> + int origin)
> +{
> + struct inode *inode = file->f_mapping->host;
> + int ret;
> +
> + switch (origin) {
> + case SEEK_END:
> + case SEEK_CUR:
> + offset = generic_file_llseek(file, offset, origin);
> + goto out;
> + case SEEK_DATA:
> + case SEEK_HOLE:
> + if (offset >= i_size_read(inode)) {
> + ret = -ENXIO;
> + goto error;
> + }
> +
> + ret = xfs_seek_extent(inode, &offset, origin);
> + if (ret)
> + goto error;
> + }
> +
> + if (offset != file->f_pos)
> + file->f_pos = offset;
> +
> +out:
> + return offset;
> +
> +error:
> + return ret;
> +}
> +
> const struct file_operations xfs_file_operations = {
> - .llseek = generic_file_llseek,
> + .llseek = xfs_file_llseek,
> .read = do_sync_read,
> .write = do_sync_write,
> .aio_read = xfs_file_aio_read,
_______________________________________________
xfs mailing list
xfs@xxxxxxxxxxx
http://oss.sgi.com/mailman/listinfo/xfs
