On Fri, 2013-02-22 at 07:43 +0800, Asias He wrote:
> On 02/22/2013 06:41 AM, Nicholas A. Bellinger wrote:
> > On Thu, 2013-02-21 at 15:51 +0800, Asias He wrote:
> >> This patch adds support for emulation of UNMAP within
> >> fd_execute_unmap() backend code.
> >>
> >> If the FILEIO backend is normal file, the emulation uses fallocate to
> >> punch hole to reclaim the free space used by the file. If the FILEIO
> >> backend is block device, the emulation uses blkdev_issue_discard().
> >>
> >> TODO: fd_execute_unmap() is heavliy based on iblock_execute_unmap().
> >> Will split out and share the common code.
> >>
> >> Cc: Christoph Hellwig <hch@xxxxxx>
> >> Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
> >> Cc: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> >> Signed-off-by: Asias He <asias@xxxxxxxxxx>
> >> ---
> >> drivers/target/target_core_file.c | 111 ++++++++++++++++++++++++++++++++++++++
> >> 1 file changed, 111 insertions(+)
> >>
<SNIP>
> >> + if (S_ISBLK(inode->i_mode)) {
> >> + /* The backend is block device, use discard */
> >> + struct block_device *bdev = inode->i_bdev;
> >> +
> >> + err = blkdev_issue_discard(bdev, lba, range, GFP_KERNEL, 0);
> >> + if (err < 0) {
> >> + pr_err("FILEIO: blkdev_issue_discard() failed: %d\n",
> >> + err);
> >> + ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> >> + goto err;
> >> + }
> >> + } else {
> >> + /* The backend is normal file, use fallocate */
> >> + loff_t pos = lba * dev->dev_attrib.block_size;
> >> + unsigned int len = range * dev->dev_attrib.block_size;
> >> + int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
> >> +
> >> + if (!file->f_op->fallocate) {
> >> + ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> >> + goto err;
> >> + }
> >> + err = file->f_op->fallocate(file, mode, pos, len);
> >> + if (err < 0) {
> >> + pr_warn("FILEIO: fallocate() failed: %d\n", err);
> >> + ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> >> + goto err;
> >> + }
> >> + }
> >> +
> >
> > Moving the if (S_ISBLK(inode->i_mode) { .. } else { .. } blocks into a
> > separate function that can be shared by fd_execute_write_same_unmap()
> > would save a few LOC here.
>
> Yes, exactly. Also we only need !file->f_op->fallocate check once.
>
> BTW, which file is the best place to put common code for
> fd_execute_unmap() and iblock_execute_unmap().
>
Common code for unmap emulation can go into target_core_sbc.c
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