1 files changed, 218 insertions, 0 deletions
diff --git a/fs/xfs/xfs_discard.c b/fs/xfs/xfs_discard.c
new file mode 100644
index 000000000..bfc829c07
--- /dev/null
+++ b/fs/xfs/xfs_discard.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2010 Red Hat, Inc.
+ * All Rights Reserved.
+ */
+#include "xfs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_btree.h"
+#include "xfs_alloc_btree.h"
+#include "xfs_alloc.h"
+#include "xfs_discard.h"
+#include "xfs_error.h"
+#include "xfs_extent_busy.h"
+#include "xfs_trace.h"
+#include "xfs_log.h"
+#include "xfs_ag.h"
+
+STATIC int
+xfs_trim_extents(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno,
+	xfs_daddr_t		start,
+	xfs_daddr_t		end,
+	xfs_daddr_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_agf		*agf;
+	struct xfs_perag	*pag;
+	int			error;
+	int			i;
+
+	pag = xfs_perag_get(mp, agno);
+
+	/*
+	 * Force out the log.  This means any transactions that might have freed
+	 * space before we take the AGF buffer lock are now on disk, and the
+	 * volatile disk cache is flushed.
+	 */
+	xfs_log_force(mp, XFS_LOG_SYNC);
+
+	error = xfs_alloc_read_agf(pag, NULL, 0, &agbp);
+	if (error)
+		goto out_put_perag;
+	agf = agbp->b_addr;
+
+	cur = xfs_allocbt_init_cursor(mp, NULL, agbp, pag, XFS_BTNUM_CNT);
+
+	/*
+	 * Look up the longest btree in the AGF and start with it.
+	 */
+	error = xfs_alloc_lookup_ge(cur, 0, be32_to_cpu(agf->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;
+		xfs_daddr_t	dbno;
+		xfs_extlen_t	dlen;
+
+		error = xfs_alloc_get_rec(cur, &fbno, &flen, &i);
+		if (error)
+			goto out_del_cursor;
+		if (XFS_IS_CORRUPT(mp, i != 1)) {
+			error = -EFSCORRUPTED;
+			goto out_del_cursor;
+		}
+		ASSERT(flen <= be32_to_cpu(agf->agf_longest));
+
+		/*
+		 * use daddr format for all range/len calculations as that is
+		 * the format the range/len variables are supplied in by
+		 * userspace.
+		 */
+		dbno = XFS_AGB_TO_DADDR(mp, agno, fbno);
+		dlen = XFS_FSB_TO_BB(mp, flen);
+
+		/*
+		 * Too small?  Give up.
+		 */
+		if (dlen < 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 (dbno + dlen < start || dbno > 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_extent_busy_search(mp, pag, 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, dbno, dlen, GFP_NOFS);
+		if (error)
+			goto out_del_cursor;
+		*blocks_trimmed += flen;
+
+next_extent:
+		error = xfs_btree_decrement(cur, 0, &i);
+		if (error)
+			goto out_del_cursor;
+
+		if (fatal_signal_pending(current)) {
+			error = -ERESTARTSYS;
+			goto out_del_cursor;
+		}
+	}
+
+out_del_cursor:
+	xfs_btree_del_cursor(cur, error);
+	xfs_buf_relse(agbp);
+out_put_perag:
+	xfs_perag_put(pag);
+	return error;
+}
+
+/*
+ * trim a range of the filesystem.
+ *
+ * Note: the parameters passed from userspace are byte ranges into the
+ * filesystem which does not match to the format we use for filesystem block
+ * addressing. FSB addressing is sparse (AGNO|AGBNO), while the incoming format
+ * is a linear address range. Hence we need to use DADDR based conversions and
+ * comparisons for determining the correct offset and regions to trim.
+ */
+int
+xfs_ioc_trim(
+	struct xfs_mount		*mp,
+	struct fstrim_range __user	*urange)
+{
+	unsigned int		granularity =
+		bdev_discard_granularity(mp->m_ddev_targp->bt_bdev);
+	struct fstrim_range	range;
+	xfs_daddr_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 -EPERM;
+	if (!bdev_max_discard_sectors(mp->m_ddev_targp->bt_bdev))
+		return -EOPNOTSUPP;
+
+	/*
+	 * We haven't recovered the log, so we cannot use our bnobt-guided
+	 * storage zapping commands.
+	 */
+	if (xfs_has_norecovery(mp))
+		return -EROFS;
+
+	if (copy_from_user(&range, urange, sizeof(range)))
+		return -EFAULT;
+
+	range.minlen = max_t(u64, granularity, range.minlen);
+	minlen = BTOBB(range.minlen);
+	/*
+	 * Truncating down the len isn't actually quite correct, but using
+	 * BBTOB 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.
+	 */
+	if (range.start >= XFS_FSB_TO_B(mp, mp->m_sb.sb_dblocks) ||
+	    range.minlen > XFS_FSB_TO_B(mp, mp->m_ag_max_usable) ||
+	    range.len < mp->m_sb.sb_blocksize)
+		return -EINVAL;
+
+	start = BTOBB(range.start);
+	end = start + BTOBBT(range.len) - 1;
+
+	if (end > XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks) - 1)
+		end = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks)- 1;
+
+	start_agno = xfs_daddr_to_agno(mp, start);
+	end_agno = xfs_daddr_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 (error == -ERESTARTSYS)
+				break;
+		}
+	}
+
+	if (last_error)
+		return last_error;
+
+	range.len = XFS_FSB_TO_B(mp, blocks_trimmed);
+	if (copy_to_user(urange, &range, sizeof(range)))
+		return -EFAULT;
+	return 0;
+}