xfs: implement the GETFSMAP ioctl
Introduce a new ioctl that uses the reverse mapping btree to return
information about the physical layout of the filesystem.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
new file mode 100644
index 0000000..24b3e53
--- /dev/null
+++ b/fs/xfs/xfs_fsmap.c
@@ -0,0 +1,756 @@
+/*
+ * Copyright (C) 2017 Oracle. All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * 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 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_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_defer.h"
+#include "xfs_inode.h"
+#include "xfs_trans.h"
+#include "xfs_error.h"
+#include "xfs_btree.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_trace.h"
+#include "xfs_log.h"
+#include "xfs_rmap.h"
+#include "xfs_alloc.h"
+#include "xfs_bit.h"
+#include <linux/fsmap.h>
+#include "xfs_fsmap.h"
+#include "xfs_refcount.h"
+#include "xfs_refcount_btree.h"
+
+/* Convert an xfs_fsmap to an fsmap. */
+void
+xfs_fsmap_from_internal(
+ struct fsmap *dest,
+ struct xfs_fsmap *src)
+{
+ dest->fmr_device = src->fmr_device;
+ dest->fmr_flags = src->fmr_flags;
+ dest->fmr_physical = BBTOB(src->fmr_physical);
+ dest->fmr_owner = src->fmr_owner;
+ dest->fmr_offset = BBTOB(src->fmr_offset);
+ dest->fmr_length = BBTOB(src->fmr_length);
+ dest->fmr_reserved[0] = 0;
+ dest->fmr_reserved[1] = 0;
+ dest->fmr_reserved[2] = 0;
+}
+
+/* Convert an fsmap to an xfs_fsmap. */
+void
+xfs_fsmap_to_internal(
+ struct xfs_fsmap *dest,
+ struct fsmap *src)
+{
+ dest->fmr_device = src->fmr_device;
+ dest->fmr_flags = src->fmr_flags;
+ dest->fmr_physical = BTOBBT(src->fmr_physical);
+ dest->fmr_owner = src->fmr_owner;
+ dest->fmr_offset = BTOBBT(src->fmr_offset);
+ dest->fmr_length = BTOBBT(src->fmr_length);
+}
+
+/* Convert an fsmap owner into an rmapbt owner. */
+static int
+xfs_fsmap_owner_to_rmap(
+ struct xfs_rmap_irec *dest,
+ struct xfs_fsmap *src)
+{
+ if (!(src->fmr_flags & FMR_OF_SPECIAL_OWNER)) {
+ dest->rm_owner = src->fmr_owner;
+ return 0;
+ }
+
+ switch (src->fmr_owner) {
+ case 0: /* "lowest owner id possible" */
+ case -1ULL: /* "highest owner id possible" */
+ dest->rm_owner = 0;
+ break;
+ case XFS_FMR_OWN_FREE:
+ dest->rm_owner = XFS_RMAP_OWN_NULL;
+ break;
+ case XFS_FMR_OWN_UNKNOWN:
+ dest->rm_owner = XFS_RMAP_OWN_UNKNOWN;
+ break;
+ case XFS_FMR_OWN_FS:
+ dest->rm_owner = XFS_RMAP_OWN_FS;
+ break;
+ case XFS_FMR_OWN_LOG:
+ dest->rm_owner = XFS_RMAP_OWN_LOG;
+ break;
+ case XFS_FMR_OWN_AG:
+ dest->rm_owner = XFS_RMAP_OWN_AG;
+ break;
+ case XFS_FMR_OWN_INOBT:
+ dest->rm_owner = XFS_RMAP_OWN_INOBT;
+ break;
+ case XFS_FMR_OWN_INODES:
+ dest->rm_owner = XFS_RMAP_OWN_INODES;
+ break;
+ case XFS_FMR_OWN_REFC:
+ dest->rm_owner = XFS_RMAP_OWN_REFC;
+ break;
+ case XFS_FMR_OWN_COW:
+ dest->rm_owner = XFS_RMAP_OWN_COW;
+ break;
+ case XFS_FMR_OWN_DEFECTIVE: /* not implemented */
+ /* fall through */
+ default:
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/* Convert an rmapbt owner into an fsmap owner. */
+static int
+xfs_fsmap_owner_from_rmap(
+ struct xfs_fsmap *dest,
+ struct xfs_rmap_irec *src)
+{
+ dest->fmr_flags = 0;
+ if (!XFS_RMAP_NON_INODE_OWNER(src->rm_owner)) {
+ dest->fmr_owner = src->rm_owner;
+ return 0;
+ }
+ dest->fmr_flags |= FMR_OF_SPECIAL_OWNER;
+
+ switch (src->rm_owner) {
+ case XFS_RMAP_OWN_FS:
+ dest->fmr_owner = XFS_FMR_OWN_FS;
+ break;
+ case XFS_RMAP_OWN_LOG:
+ dest->fmr_owner = XFS_FMR_OWN_LOG;
+ break;
+ case XFS_RMAP_OWN_AG:
+ dest->fmr_owner = XFS_FMR_OWN_AG;
+ break;
+ case XFS_RMAP_OWN_INOBT:
+ dest->fmr_owner = XFS_FMR_OWN_INOBT;
+ break;
+ case XFS_RMAP_OWN_INODES:
+ dest->fmr_owner = XFS_FMR_OWN_INODES;
+ break;
+ case XFS_RMAP_OWN_REFC:
+ dest->fmr_owner = XFS_FMR_OWN_REFC;
+ break;
+ case XFS_RMAP_OWN_COW:
+ dest->fmr_owner = XFS_FMR_OWN_COW;
+ break;
+ default:
+ return -EFSCORRUPTED;
+ }
+ return 0;
+}
+
+/* getfsmap query state */
+struct xfs_getfsmap_info {
+ struct xfs_fsmap_head *head;
+ xfs_fsmap_format_t formatter; /* formatting fn */
+ void *format_arg; /* format buffer */
+ struct xfs_buf *agf_bp; /* AGF, for refcount queries */
+ xfs_daddr_t next_daddr; /* next daddr we expect */
+ u64 missing_owner; /* owner of holes */
+ u32 dev; /* device id */
+ xfs_agnumber_t agno; /* AG number, if applicable */
+ struct xfs_rmap_irec low; /* low rmap key */
+ struct xfs_rmap_irec high; /* high rmap key */
+ bool last; /* last extent? */
+};
+
+/* Associate a device with a getfsmap handler. */
+struct xfs_getfsmap_dev {
+ u32 dev;
+ int (*fn)(struct xfs_trans *tp,
+ struct xfs_fsmap *keys,
+ struct xfs_getfsmap_info *info);
+};
+
+/* Compare two getfsmap device handlers. */
+static int
+xfs_getfsmap_dev_compare(
+ const void *p1,
+ const void *p2)
+{
+ const struct xfs_getfsmap_dev *d1 = p1;
+ const struct xfs_getfsmap_dev *d2 = p2;
+
+ return d1->dev - d2->dev;
+}
+
+/* Decide if this mapping is shared. */
+STATIC int
+xfs_getfsmap_is_shared(
+ struct xfs_trans *tp,
+ struct xfs_getfsmap_info *info,
+ struct xfs_rmap_irec *rec,
+ bool *stat)
+{
+ struct xfs_mount *mp = tp->t_mountp;
+ struct xfs_btree_cur *cur;
+ xfs_agblock_t fbno;
+ xfs_extlen_t flen;
+ int error;
+
+ *stat = false;
+ if (!xfs_sb_version_hasreflink(&mp->m_sb))
+ return 0;
+ /* rt files will have agno set to NULLAGNUMBER */
+ if (info->agno == NULLAGNUMBER)
+ return 0;
+
+ /* Are there any shared blocks here? */
+ flen = 0;
+ cur = xfs_refcountbt_init_cursor(mp, tp, info->agf_bp,
+ info->agno, NULL);
+
+ error = xfs_refcount_find_shared(cur, rec->rm_startblock,
+ rec->rm_blockcount, &fbno, &flen, false);
+
+ xfs_btree_del_cursor(cur, error ? XFS_BTREE_ERROR : XFS_BTREE_NOERROR);
+ if (error)
+ return error;
+
+ *stat = flen > 0;
+ return 0;
+}
+
+/*
+ * Format a reverse mapping for getfsmap, having translated rm_startblock
+ * into the appropriate daddr units.
+ */
+STATIC int
+xfs_getfsmap_helper(
+ struct xfs_trans *tp,
+ struct xfs_getfsmap_info *info,
+ struct xfs_rmap_irec *rec,
+ xfs_daddr_t rec_daddr)
+{
+ struct xfs_fsmap fmr;
+ struct xfs_mount *mp = tp->t_mountp;
+ bool shared;
+ int error;
+
+ if (fatal_signal_pending(current))
+ return -EINTR;
+
+ /*
+ * Filter out records that start before our startpoint, if the
+ * caller requested that.
+ */
+ if (xfs_rmap_compare(rec, &info->low) < 0) {
+ rec_daddr += XFS_FSB_TO_BB(mp, rec->rm_blockcount);
+ if (info->next_daddr < rec_daddr)
+ info->next_daddr = rec_daddr;
+ return XFS_BTREE_QUERY_RANGE_CONTINUE;
+ }
+
+ /* Are we just counting mappings? */
+ if (info->head->fmh_count == 0) {
+ if (rec_daddr > info->next_daddr)
+ info->head->fmh_entries++;
+
+ if (info->last)
+ return XFS_BTREE_QUERY_RANGE_CONTINUE;
+
+ info->head->fmh_entries++;
+
+ rec_daddr += XFS_FSB_TO_BB(mp, rec->rm_blockcount);
+ if (info->next_daddr < rec_daddr)
+ info->next_daddr = rec_daddr;
+ return XFS_BTREE_QUERY_RANGE_CONTINUE;
+ }
+
+ /*
+ * If the record starts past the last physical block we saw,
+ * then we've found a gap. Report the gap as being owned by
+ * whatever the caller specified is the missing owner.
+ */
+ if (rec_daddr > info->next_daddr) {
+ if (info->head->fmh_entries >= info->head->fmh_count)
+ return XFS_BTREE_QUERY_RANGE_ABORT;
+
+ fmr.fmr_device = info->dev;
+ fmr.fmr_physical = info->next_daddr;
+ fmr.fmr_owner = info->missing_owner;
+ fmr.fmr_offset = 0;
+ fmr.fmr_length = rec_daddr - info->next_daddr;
+ fmr.fmr_flags = FMR_OF_SPECIAL_OWNER;
+ error = info->formatter(&fmr, info->format_arg);
+ if (error)
+ return error;
+ info->head->fmh_entries++;
+ }
+
+ if (info->last)
+ goto out;
+
+ /* Fill out the extent we found */
+ if (info->head->fmh_entries >= info->head->fmh_count)
+ return XFS_BTREE_QUERY_RANGE_ABORT;
+
+ trace_xfs_fsmap_mapping(mp, info->dev, info->agno, rec);
+
+ fmr.fmr_device = info->dev;
+ fmr.fmr_physical = rec_daddr;
+ error = xfs_fsmap_owner_from_rmap(&fmr, rec);
+ if (error)
+ return error;
+ fmr.fmr_offset = XFS_FSB_TO_BB(mp, rec->rm_offset);
+ fmr.fmr_length = XFS_FSB_TO_BB(mp, rec->rm_blockcount);
+ if (rec->rm_flags & XFS_RMAP_UNWRITTEN)
+ fmr.fmr_flags |= FMR_OF_PREALLOC;
+ if (rec->rm_flags & XFS_RMAP_ATTR_FORK)
+ fmr.fmr_flags |= FMR_OF_ATTR_FORK;
+ if (rec->rm_flags & XFS_RMAP_BMBT_BLOCK)
+ fmr.fmr_flags |= FMR_OF_EXTENT_MAP;
+ if (fmr.fmr_flags == 0) {
+ error = xfs_getfsmap_is_shared(tp, info, rec, &shared);
+ if (error)
+ return error;
+ if (shared)
+ fmr.fmr_flags |= FMR_OF_SHARED;
+ }
+ error = info->formatter(&fmr, info->format_arg);
+ if (error)
+ return error;
+ info->head->fmh_entries++;
+
+out:
+ rec_daddr += XFS_FSB_TO_BB(mp, rec->rm_blockcount);
+ if (info->next_daddr < rec_daddr)
+ info->next_daddr = rec_daddr;
+ return XFS_BTREE_QUERY_RANGE_CONTINUE;
+}
+
+/* Transform a rmapbt irec into a fsmap */
+STATIC int
+xfs_getfsmap_datadev_helper(
+ struct xfs_btree_cur *cur,
+ struct xfs_rmap_irec *rec,
+ void *priv)
+{
+ struct xfs_mount *mp = cur->bc_mp;
+ struct xfs_getfsmap_info *info = priv;
+ xfs_fsblock_t fsb;
+ xfs_daddr_t rec_daddr;
+
+ fsb = XFS_AGB_TO_FSB(mp, cur->bc_private.a.agno, rec->rm_startblock);
+ rec_daddr = XFS_FSB_TO_DADDR(mp, fsb);
+
+ return xfs_getfsmap_helper(cur->bc_tp, info, rec, rec_daddr);
+}
+
+/* Set rmap flags based on the getfsmap flags */
+static void
+xfs_getfsmap_set_irec_flags(
+ struct xfs_rmap_irec *irec,
+ struct xfs_fsmap *fmr)
+{
+ irec->rm_flags = 0;
+ if (fmr->fmr_flags & FMR_OF_ATTR_FORK)
+ irec->rm_flags |= XFS_RMAP_ATTR_FORK;
+ if (fmr->fmr_flags & FMR_OF_EXTENT_MAP)
+ irec->rm_flags |= XFS_RMAP_BMBT_BLOCK;
+ if (fmr->fmr_flags & FMR_OF_PREALLOC)
+ irec->rm_flags |= XFS_RMAP_UNWRITTEN;
+}
+
+/* Execute a getfsmap query against the log device. */
+STATIC int
+xfs_getfsmap_logdev(
+ struct xfs_trans *tp,
+ struct xfs_fsmap *keys,
+ struct xfs_getfsmap_info *info)
+{
+ struct xfs_mount *mp = tp->t_mountp;
+ struct xfs_rmap_irec rmap;
+ int error;
+
+ /* Set up search keys */
+ info->low.rm_startblock = XFS_BB_TO_FSBT(mp, keys[0].fmr_physical);
+ info->low.rm_offset = XFS_BB_TO_FSBT(mp, keys[0].fmr_offset);
+ error = xfs_fsmap_owner_to_rmap(&info->low, keys);
+ if (error)
+ return error;
+ info->low.rm_blockcount = 0;
+ xfs_getfsmap_set_irec_flags(&info->low, &keys[0]);
+
+ error = xfs_fsmap_owner_to_rmap(&info->high, keys + 1);
+ if (error)
+ return error;
+ info->high.rm_startblock = -1U;
+ info->high.rm_owner = ULLONG_MAX;
+ info->high.rm_offset = ULLONG_MAX;
+ info->high.rm_blockcount = 0;
+ info->high.rm_flags = XFS_RMAP_KEY_FLAGS | XFS_RMAP_REC_FLAGS;
+ info->missing_owner = XFS_FMR_OWN_FREE;
+
+ trace_xfs_fsmap_low_key(mp, info->dev, info->agno, &info->low);
+ trace_xfs_fsmap_high_key(mp, info->dev, info->agno, &info->high);
+
+ if (keys[0].fmr_physical > 0)
+ return 0;
+
+ /* Fabricate an rmap entry for the external log device. */
+ rmap.rm_startblock = 0;
+ rmap.rm_blockcount = mp->m_sb.sb_logblocks;
+ rmap.rm_owner = XFS_RMAP_OWN_LOG;
+ rmap.rm_offset = 0;
+ rmap.rm_flags = 0;
+
+ return xfs_getfsmap_helper(tp, info, &rmap, 0);
+}
+
+/* Execute a getfsmap query against the regular data device. */
+STATIC int
+__xfs_getfsmap_datadev(
+ struct xfs_trans *tp,
+ struct xfs_fsmap *keys,
+ struct xfs_getfsmap_info *info,
+ int (*query_fn)(struct xfs_trans *,
+ struct xfs_getfsmap_info *,
+ struct xfs_btree_cur **,
+ void *),
+ void *priv)
+{
+ struct xfs_mount *mp = tp->t_mountp;
+ struct xfs_btree_cur *bt_cur = NULL;
+ xfs_fsblock_t start_fsb;
+ xfs_fsblock_t end_fsb;
+ xfs_agnumber_t start_ag;
+ xfs_agnumber_t end_ag;
+ xfs_daddr_t eofs;
+ int error = 0;
+
+ eofs = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
+ if (keys[0].fmr_physical >= eofs)
+ return 0;
+ if (keys[1].fmr_physical >= eofs)
+ keys[1].fmr_physical = eofs - 1;
+ start_fsb = XFS_DADDR_TO_FSB(mp, keys[0].fmr_physical);
+ end_fsb = XFS_DADDR_TO_FSB(mp, keys[1].fmr_physical);
+
+ /*
+ * Convert the fsmap low/high keys to AG based keys. Initialize
+ * low to the fsmap low key and max out the high key to the end
+ * of the AG.
+ */
+ info->low.rm_startblock = XFS_FSB_TO_AGBNO(mp, start_fsb);
+ info->low.rm_offset = XFS_BB_TO_FSBT(mp, keys[0].fmr_offset);
+ error = xfs_fsmap_owner_to_rmap(&info->low, &keys[0]);
+ if (error)
+ return error;
+ info->low.rm_blockcount = 0;
+ xfs_getfsmap_set_irec_flags(&info->low, &keys[0]);
+
+ info->high.rm_startblock = -1U;
+ info->high.rm_owner = ULLONG_MAX;
+ info->high.rm_offset = ULLONG_MAX;
+ info->high.rm_blockcount = 0;
+ info->high.rm_flags = XFS_RMAP_KEY_FLAGS | XFS_RMAP_REC_FLAGS;
+
+ start_ag = XFS_FSB_TO_AGNO(mp, start_fsb);
+ end_ag = XFS_FSB_TO_AGNO(mp, end_fsb);
+
+ /* Query each AG */
+ for (info->agno = start_ag; info->agno <= end_ag; info->agno++) {
+ /*
+ * Set the AG high key from the fsmap high key if this
+ * is the last AG that we're querying.
+ */
+ if (info->agno == end_ag) {
+ info->high.rm_startblock = XFS_FSB_TO_AGBNO(mp,
+ end_fsb);
+ info->high.rm_offset = XFS_BB_TO_FSBT(mp,
+ keys[1].fmr_offset);
+ error = xfs_fsmap_owner_to_rmap(&info->high, &keys[1]);
+ if (error)
+ goto err;
+ xfs_getfsmap_set_irec_flags(&info->high, &keys[1]);
+ }
+
+ if (bt_cur) {
+ xfs_btree_del_cursor(bt_cur, XFS_BTREE_NOERROR);
+ bt_cur = NULL;
+ xfs_trans_brelse(tp, info->agf_bp);
+ info->agf_bp = NULL;
+ }
+
+ error = xfs_alloc_read_agf(mp, tp, info->agno, 0,
+ &info->agf_bp);
+ if (error)
+ goto err;
+
+ trace_xfs_fsmap_low_key(mp, info->dev, info->agno, &info->low);
+ trace_xfs_fsmap_high_key(mp, info->dev, info->agno,
+ &info->high);
+
+ error = query_fn(tp, info, &bt_cur, priv);
+ if (error)
+ goto err;
+
+ /*
+ * Set the AG low key to the start of the AG prior to
+ * moving on to the next AG.
+ */
+ if (info->agno == start_ag) {
+ info->low.rm_startblock = 0;
+ info->low.rm_owner = 0;
+ info->low.rm_offset = 0;
+ info->low.rm_flags = 0;
+ }
+ }
+
+ /* Report any gap at the end of the AG */
+ info->last = true;
+ error = query_fn(tp, info, &bt_cur, priv);
+ if (error)
+ goto err;
+
+err:
+ if (bt_cur)
+ xfs_btree_del_cursor(bt_cur, error < 0 ? XFS_BTREE_ERROR :
+ XFS_BTREE_NOERROR);
+ if (info->agf_bp) {
+ xfs_trans_brelse(tp, info->agf_bp);
+ info->agf_bp = NULL;
+ }
+
+ return error;
+}
+
+/* Actually query the rmap btree. */
+STATIC int
+xfs_getfsmap_datadev_rmapbt_query(
+ struct xfs_trans *tp,
+ struct xfs_getfsmap_info *info,
+ struct xfs_btree_cur **curpp,
+ void *priv)
+{
+ /* Report any gap at the end of the last AG. */
+ if (info->last)
+ return xfs_getfsmap_datadev_helper(*curpp, &info->high, info);
+
+ /* Allocate cursor for this AG and query_range it. */
+ *curpp = xfs_rmapbt_init_cursor(tp->t_mountp, tp, info->agf_bp,
+ info->agno);
+ return xfs_rmap_query_range(*curpp, &info->low, &info->high,
+ xfs_getfsmap_datadev_helper, info);
+}
+
+/* Execute a getfsmap query against the regular data device rmapbt. */
+STATIC int
+xfs_getfsmap_datadev_rmapbt(
+ struct xfs_trans *tp,
+ struct xfs_fsmap *keys,
+ struct xfs_getfsmap_info *info)
+{
+ info->missing_owner = XFS_FMR_OWN_FREE;
+ return __xfs_getfsmap_datadev(tp, keys, info,
+ xfs_getfsmap_datadev_rmapbt_query, NULL);
+}
+
+/* Do we recognize the device? */
+STATIC bool
+xfs_getfsmap_is_valid_device(
+ struct xfs_mount *mp,
+ struct xfs_fsmap *fm)
+{
+ if (fm->fmr_device == 0 || fm->fmr_device == UINT_MAX ||
+ fm->fmr_device == new_encode_dev(mp->m_ddev_targp->bt_dev))
+ return true;
+ if (mp->m_logdev_targp &&
+ fm->fmr_device == new_encode_dev(mp->m_logdev_targp->bt_dev))
+ return true;
+ return false;
+}
+
+/* Ensure that the low key is less than the high key. */
+STATIC bool
+xfs_getfsmap_check_keys(
+ struct xfs_fsmap *low_key,
+ struct xfs_fsmap *high_key)
+{
+ if (low_key->fmr_device > high_key->fmr_device)
+ return false;
+ if (low_key->fmr_device < high_key->fmr_device)
+ return true;
+
+ if (low_key->fmr_physical > high_key->fmr_physical)
+ return false;
+ if (low_key->fmr_physical < high_key->fmr_physical)
+ return true;
+
+ if (low_key->fmr_owner > high_key->fmr_owner)
+ return false;
+ if (low_key->fmr_owner < high_key->fmr_owner)
+ return true;
+
+ if (low_key->fmr_offset > high_key->fmr_offset)
+ return false;
+ if (low_key->fmr_offset < high_key->fmr_offset)
+ return true;
+
+ return false;
+}
+
+#define XFS_GETFSMAP_DEVS 2
+/*
+ * Get filesystem's extents as described in head, and format for
+ * output. Calls formatter to fill the user's buffer until all
+ * extents are mapped, until the passed-in head->fmh_count slots have
+ * been filled, or until the formatter short-circuits the loop, if it
+ * is tracking filled-in extents on its own.
+ *
+ * Key to Confusion
+ * ----------------
+ * There are multiple levels of keys and counters at work here:
+ * xfs_fsmap_head.fmh_keys -- low and high fsmap keys passed in;
+ * these reflect fs-wide sector addrs.
+ * dkeys -- fmh_keys used to query each device;
+ * these are fmh_keys but w/ the low key
+ * bumped up by fmr_length.
+ * xfs_getfsmap_info.next_daddr -- next disk addr we expect to see; this
+ * is how we detect gaps in the fsmap
+ records and report them.
+ * xfs_getfsmap_info.low/high -- per-AG low/high keys computed from
+ * dkeys; used to query the metadata.
+ */
+int
+xfs_getfsmap(
+ struct xfs_mount *mp,
+ struct xfs_fsmap_head *head,
+ xfs_fsmap_format_t formatter,
+ void *arg)
+{
+ struct xfs_trans *tp = NULL;
+ struct xfs_fsmap dkeys[2]; /* per-dev keys */
+ struct xfs_getfsmap_dev handlers[XFS_GETFSMAP_DEVS];
+ struct xfs_getfsmap_info info = {0};
+ int i;
+ int error = 0;
+
+ if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+ return -EOPNOTSUPP;
+ if (head->fmh_iflags & ~FMH_IF_VALID)
+ return -EINVAL;
+ if (!xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[0]) ||
+ !xfs_getfsmap_is_valid_device(mp, &head->fmh_keys[1]))
+ return -EINVAL;
+
+ head->fmh_entries = 0;
+
+ /* Set up our device handlers. */
+ memset(handlers, 0, sizeof(handlers));
+ handlers[0].dev = new_encode_dev(mp->m_ddev_targp->bt_dev);
+ handlers[0].fn = xfs_getfsmap_datadev_rmapbt;
+ if (mp->m_logdev_targp != mp->m_ddev_targp) {
+ handlers[1].dev = new_encode_dev(mp->m_logdev_targp->bt_dev);
+ handlers[1].fn = xfs_getfsmap_logdev;
+ }
+
+ xfs_sort(handlers, XFS_GETFSMAP_DEVS, sizeof(struct xfs_getfsmap_dev),
+ xfs_getfsmap_dev_compare);
+
+ /*
+ * To continue where we left off, we allow userspace to use the
+ * last mapping from a previous call as the low key of the next.
+ * This is identified by a non-zero length in the low key. We
+ * have to increment the low key in this scenario to ensure we
+ * don't return the same mapping again, and instead return the
+ * very next mapping.
+ *
+ * If the low key mapping refers to file data, the same physical
+ * blocks could be mapped to several other files/offsets.
+ * According to rmapbt record ordering, the minimal next
+ * possible record for the block range is the next starting
+ * offset in the same inode. Therefore, bump the file offset to
+ * continue the search appropriately. For all other low key
+ * mapping types (attr blocks, metadata), bump the physical
+ * offset as there can be no other mapping for the same physical
+ * block range.
+ */
+ dkeys[0] = head->fmh_keys[0];
+ if (dkeys[0].fmr_flags & (FMR_OF_SPECIAL_OWNER | FMR_OF_EXTENT_MAP)) {
+ dkeys[0].fmr_physical += dkeys[0].fmr_length;
+ dkeys[0].fmr_owner = 0;
+ if (dkeys[0].fmr_offset)
+ return -EINVAL;
+ } else
+ dkeys[0].fmr_offset += dkeys[0].fmr_length;
+ dkeys[0].fmr_length = 0;
+ memset(&dkeys[1], 0xFF, sizeof(struct xfs_fsmap));
+
+ if (!xfs_getfsmap_check_keys(dkeys, &head->fmh_keys[1]))
+ return -EINVAL;
+
+ info.next_daddr = head->fmh_keys[0].fmr_physical +
+ head->fmh_keys[0].fmr_length;
+ info.formatter = formatter;
+ info.format_arg = arg;
+ info.head = head;
+
+ /* For each device we support... */
+ for (i = 0; i < XFS_GETFSMAP_DEVS; i++) {
+ /* Is this device within the range the user asked for? */
+ if (!handlers[i].fn)
+ continue;
+ if (head->fmh_keys[0].fmr_device > handlers[i].dev)
+ continue;
+ if (head->fmh_keys[1].fmr_device < handlers[i].dev)
+ break;
+
+ /*
+ * If this device number matches the high key, we have
+ * to pass the high key to the handler to limit the
+ * query results. If the device number exceeds the
+ * low key, zero out the low key so that we get
+ * everything from the beginning.
+ */
+ if (handlers[i].dev == head->fmh_keys[1].fmr_device)
+ dkeys[1] = head->fmh_keys[1];
+ if (handlers[i].dev > head->fmh_keys[0].fmr_device)
+ memset(&dkeys[0], 0, sizeof(struct xfs_fsmap));
+
+ error = xfs_trans_alloc_empty(mp, &tp);
+ if (error)
+ break;
+
+ info.dev = handlers[i].dev;
+ info.last = false;
+ info.agno = NULLAGNUMBER;
+ error = handlers[i].fn(tp, dkeys, &info);
+ if (error)
+ break;
+ xfs_trans_cancel(tp);
+ tp = NULL;
+ info.next_daddr = 0;
+ }
+
+ if (tp)
+ xfs_trans_cancel(tp);
+ head->fmh_oflags = FMH_OF_DEV_T;
+ return error;
+}