/*
   * Copyright (C) 2010 Red Hat, Inc.
   * All Rights Reserved.
   *
   * 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.
   *
   * This program is distributed in the hope that it would 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 the Free Software Foundation,
   * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */
  #include "xfs.h"
  #include "xfs_sb.h"
  #include "xfs_inum.h"
  #include "xfs_log.h"
  #include "xfs_ag.h"
  #include "xfs_mount.h"
  #include "xfs_quota.h"
  #include "xfs_trans.h"
  #include "xfs_alloc_btree.h"
  #include "xfs_bmap_btree.h"
  #include "xfs_ialloc_btree.h"
  #include "xfs_btree.h"
  #include "xfs_inode.h"
  #include "xfs_alloc.h"
  #include "xfs_error.h"
  #include "xfs_discard.h"
  #include "xfs_trace.h"
  
  STATIC int
  xfs_trim_extents(
  	struct xfs_mount	*mp,
  	xfs_agnumber_t		agno,
  	xfs_fsblock_t		start,

  	xfs_fsblock_t		end,

  	xfs_fsblock_t		minlen,
  	__uint64_t		*blocks_trimmed)
  {
  	struct block_device	*bdev = mp->m_ddev_targp->bt_bdev;
  	struct xfs_btree_cur	*cur;
  	struct xfs_buf		*agbp;
  	struct xfs_perag	*pag;
  	int			error;
  	int			i;
  
  	pag = xfs_perag_get(mp, agno);
  
  	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
  	if (error || !agbp)
  		goto out_put_perag;
  
  	cur = xfs_allocbt_init_cursor(mp, NULL, agbp, agno, XFS_BTNUM_CNT);
  
  	/*
  	 * Force out the log.  This means any transactions that might have freed
  	 * space before we took the AGF buffer lock are now on disk, and the
  	 * volatile disk cache is flushed.
  	 */
  	xfs_log_force(mp, XFS_LOG_SYNC);
  
  	/*
  	 * Look up the longest btree in the AGF and start with it.
  	 */
  	error = xfs_alloc_lookup_le(cur, 0,
  				    XFS_BUF_TO_AGF(agbp)->agf_longest, &i);
  	if (error)
  		goto out_del_cursor;
  
  	/*
  	 * Loop until we are done with all extents that are large
  	 * enough to be worth discarding.
  	 */
  	while (i) {
  		xfs_agblock_t fbno;
  		xfs_extlen_t flen;
  
  		error = xfs_alloc_get_rec(cur, &fbno, &flen, &i);
  		if (error)
  			goto out_del_cursor;
  		XFS_WANT_CORRUPTED_GOTO(i == 1, out_del_cursor);
  		ASSERT(flen <= XFS_BUF_TO_AGF(agbp)->agf_longest);
  
  		/*
  		 * Too small?  Give up.
  		 */
  		if (flen < minlen) {
  			trace_xfs_discard_toosmall(mp, agno, fbno, flen);
  			goto out_del_cursor;
  		}
  
  		/*
  		 * If the extent is entirely outside of the range we are
  		 * supposed to discard skip it.  Do not bother to trim
  		 * down partially overlapping ranges for now.
  		 */
  		if (XFS_AGB_TO_FSB(mp, agno, fbno) + flen < start ||

  		    XFS_AGB_TO_FSB(mp, agno, fbno) > end) {

  			trace_xfs_discard_exclude(mp, agno, fbno, flen);
  			goto next_extent;
  		}
  
  		/*
  		 * If any blocks in the range are still busy, skip the
  		 * discard and try again the next time.
  		 */
  		if (xfs_alloc_busy_search(mp, agno, fbno, flen)) {
  			trace_xfs_discard_busy(mp, agno, fbno, flen);
  			goto next_extent;
  		}
  
  		trace_xfs_discard_extent(mp, agno, fbno, flen);
  		error = -blkdev_issue_discard(bdev,
  				XFS_AGB_TO_DADDR(mp, agno, fbno),
  				XFS_FSB_TO_BB(mp, flen),
  				GFP_NOFS, 0);
  		if (error)
  			goto out_del_cursor;
  		*blocks_trimmed += flen;
  
  next_extent:
  		error = xfs_btree_decrement(cur, 0, &i);
  		if (error)
  			goto out_del_cursor;
  	}
  
  out_del_cursor:
  	xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
  	xfs_buf_relse(agbp);
  out_put_perag:
  	xfs_perag_put(pag);
  	return error;
  }
  
  int
  xfs_ioc_trim(
  	struct xfs_mount		*mp,
  	struct fstrim_range __user	*urange)
  {
  	struct request_queue	*q = mp->m_ddev_targp->bt_bdev->bd_disk->queue;
  	unsigned int		granularity = q->limits.discard_granularity;
  	struct fstrim_range	range;

  	xfs_fsblock_t		start, end, minlen;

  	xfs_agnumber_t		start_agno, end_agno, agno;
  	__uint64_t		blocks_trimmed = 0;
  	int			error, last_error = 0;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -XFS_ERROR(EPERM);

  	if (!blk_queue_discard(q))
  		return -XFS_ERROR(EOPNOTSUPP);

  	if (copy_from_user(&range, urange, sizeof(range)))
  		return -XFS_ERROR(EFAULT);
  
  	/*
  	 * Truncating down the len isn't actually quite correct, but using
  	 * XFS_B_TO_FSB would mean we trivially get overflows for values
  	 * of ULLONG_MAX or slightly lower.  And ULLONG_MAX is the default
  	 * used by the fstrim application.  In the end it really doesn't
  	 * matter as trimming blocks is an advisory interface.
  	 */
  	start = XFS_B_TO_FSBT(mp, range.start);

  	end = start + XFS_B_TO_FSBT(mp, range.len) - 1;

  	minlen = XFS_B_TO_FSB(mp, max_t(u64, granularity, range.minlen));

  	if (start >= mp->m_sb.sb_dblocks)

  		return -XFS_ERROR(EINVAL);

  	if (end > mp->m_sb.sb_dblocks - 1)
  		end = mp->m_sb.sb_dblocks - 1;

  	start_agno = XFS_FSB_TO_AGNO(mp, start);
  	end_agno = XFS_FSB_TO_AGNO(mp, end);

  
  	for (agno = start_agno; agno <= end_agno; agno++) {

  		error = -xfs_trim_extents(mp, agno, start, end, minlen,

  					  &blocks_trimmed);
  		if (error)
  			last_error = error;
  	}
  
  	if (last_error)
  		return last_error;
  
  	range.len = XFS_FSB_TO_B(mp, blocks_trimmed);
  	if (copy_to_user(urange, &range, sizeof(range)))
  		return -XFS_ERROR(EFAULT);
  	return 0;
  }

  
  int
  xfs_discard_extents(
  	struct xfs_mount	*mp,
  	struct list_head	*list)
  {
  	struct xfs_busy_extent	*busyp;
  	int			error = 0;
  
  	list_for_each_entry(busyp, list, list) {
  		trace_xfs_discard_extent(mp, busyp->agno, busyp->bno,
  					 busyp->length);
  
  		error = -blkdev_issue_discard(mp->m_ddev_targp->bt_bdev,
  				XFS_AGB_TO_DADDR(mp, busyp->agno, busyp->bno),
  				XFS_FSB_TO_BB(mp, busyp->length),
  				GFP_NOFS, 0);
  		if (error && error != EOPNOTSUPP) {
  			xfs_info(mp,
  	 "discard failed for extent [0x%llu,%u], error %d",
  				 (unsigned long long)busyp->bno,
  				 busyp->length,
  				 error);
  			return error;
  		}
  	}
  
  	return 0;
  }