jfs_discard.c

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/*
 *   Copyright (C) Tino Reichardt, 2012
 *
 *   This program is free software;  you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program;  if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/blkdev.h>

#include "jfs_incore.h"
#include "jfs_superblock.h"
#include "jfs_discard.h"
#include "jfs_dmap.h"
#include "jfs_debug.h"


/*
 * NAME:    jfs_issue_discard()
 *
 * FUNCTION:    TRIM the specified block range on device, if supported
 *
 * PARAMETERS:
 *  ip  - pointer to in-core inode
 *  blkno   - starting block number to be trimmed (0..N)
 *  nblocks - number of blocks to be trimmed
 *
 * RETURN VALUES:
 *  none
 *
 * serialization: IREAD_LOCK(ipbmap) held on entry/exit;
 */
void jfs_issue_discard(struct inode *ip, u64 blkno, u64 nblocks)
{
    struct super_block *sb = ip->i_sb;
    int r = 0;

    r = sb_issue_discard(sb, blkno, nblocks, GFP_NOFS, 0);
    if (unlikely(r != 0)) {
        jfs_err("JFS: sb_issue_discard" \
            "(%p, %llu, %llu, GFP_NOFS, 0) = %d => failed!\n",
            sb, (unsigned long long)blkno,
            (unsigned long long)nblocks, r);
    }

    jfs_info("JFS: sb_issue_discard" \
        "(%p, %llu, %llu, GFP_NOFS, 0) = %d\n",
        sb, (unsigned long long)blkno,
        (unsigned long long)nblocks, r);

    return;
}

/*
 * NAME:    jfs_ioc_trim()
 *
 * FUNCTION:    attempt to discard (TRIM) all free blocks from the
 *              filesystem.
 *
 * PARAMETERS:
 *  ip  - pointer to in-core inode;
 *  range   - the range, given by user space
 *
 * RETURN VALUES:
 *  0   - success
 *  -EIO    - i/o error
 */
int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range)
{
    struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
    struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
    struct super_block *sb = ipbmap->i_sb;
    int agno, agno_end;
    u64 start, end, minlen;
    u64 trimmed = 0;

    start = range->start >> sb->s_blocksize_bits;
    end = start + (range->len >> sb->s_blocksize_bits) - 1;
    minlen = range->minlen >> sb->s_blocksize_bits;
    if (minlen == 0)
        minlen = 1;

    if (minlen > bmp->db_agsize ||
        start >= bmp->db_mapsize ||
        range->len < sb->s_blocksize)
        return -EINVAL;

    if (end >= bmp->db_mapsize)
        end = bmp->db_mapsize - 1;

    agno = BLKTOAG(start, JFS_SBI(ip->i_sb));
    agno_end = BLKTOAG(end, JFS_SBI(ip->i_sb));
    while (agno <= agno_end) {
        trimmed += dbDiscardAG(ip, agno, minlen);
        agno++;
    }
    range->len = trimmed << sb->s_blocksize_bits;

    return 0;
}