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[PATCH 47/47] xfs: introduce the XFS_IOC_GETFSMAP ioctl

To: david@xxxxxxxxxxxxx, darrick.wong@xxxxxxxxxx
Subject: [PATCH 47/47] xfs: introduce the XFS_IOC_GETFSMAP ioctl
From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
Date: Wed, 20 Jul 2016 22:01:15 -0700
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, vishal.l.verma@xxxxxxxxx, bfoster@xxxxxxxxxx, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <146907695530.25461.3225785294902719773.stgit@xxxxxxxxxxxxxxxx>
References: <146907695530.25461.3225785294902719773.stgit@xxxxxxxxxxxxxxxx>
User-agent: StGit/0.17.1-dirty
Introduce a new ioctl that uses the reverse mapping btree to return
information about the physical layout of the filesystem.

v2: shorten the device field to u32 since that's all we need for
dev_t.  Support reporting reverse mapping information for all the
devices that XFS supports (data, log).

Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_fs.h |   65 ++++++
 fs/xfs/xfs_fsops.c     |  528 ++++++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_fsops.h     |    6 +
 fs/xfs/xfs_ioctl.c     |   76 +++++++
 fs/xfs/xfs_ioctl32.c   |    1 
 fs/xfs/xfs_trace.h     |   76 +++++++
 6 files changed, 752 insertions(+)


diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index 7945505..b08f23d 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -91,6 +91,70 @@ struct getbmapx {
 #define BMV_OF_LAST            0x4     /* segment is the last in the file */
 
 /*
+ *     Structure for XFS_IOC_GETFSMAP.
+ *
+ *     Similar to XFS_IOC_GETBMAPX, the first two elements in the array are
+ *     used to constrain the output.  The first element in the array should
+ *     represent the lowest disk address that the user wants to learn about.
+ *     The second element in the array should represent the highest disk
+ *     address to query.  Subsequent array elements will be filled out by the
+ *     command.
+ *
+ *     The fmv_iflags field is only used in the first structure.  The
+ *     fmv_oflags field is filled in for each returned structure after the
+ *     second structure.  The fmv_unused1 fields in the first two array
+ *     elements must be zero.
+ *
+ *     The fmv_count, fmv_entries, and fmv_iflags fields in the second array
+ *     element must be zero.
+ *
+ *     fmv_block, fmv_offset, and fmv_length are expressed in units of 512
+ *     byte sectors.
+ */
+#ifndef HAVE_GETFSMAP
+struct getfsmap {
+       __u32           fmv_device;     /* device id */
+       __u32           fmv_unused1;    /* future use, must be zero */
+       __u64           fmv_block;      /* starting block */
+       __u64           fmv_owner;      /* owner id */
+       __u64           fmv_offset;     /* file offset of segment */
+       __u64           fmv_length;     /* length of segment, blocks */
+       __u32           fmv_oflags;     /* mapping flags */
+       __u32           fmv_iflags;     /* control flags (1st structure) */
+       __u32           fmv_count;      /* # of entries in array incl. input */
+       __u32           fmv_entries;    /* # of entries filled in (output). */
+       __u64           fmv_unused2;    /* future use, must be zero */
+};
+#endif
+
+/*     fmv_iflags values - set by XFS_IOC_GETFSMAP caller in the header. */
+/* no flags defined yet */
+#define FMV_HIF_VALID          0
+
+/*     fmv_oflags values - returned in the header segment only. */
+#define FMV_HOF_DEV_T          0x1     /* fmv_device values will be dev_t */
+
+/*     fmv_flags values - returned for each non-header segment */
+#define FMV_OF_PREALLOC                0x1     /* segment = unwritten 
pre-allocation */
+#define FMV_OF_ATTR_FORK       0x2     /* segment = attribute fork */
+#define FMV_OF_EXTENT_MAP      0x4     /* segment = extent map */
+#define FMV_OF_SHARED          0x8     /* segment = shared with another file */
+#define FMV_OF_SPECIAL_OWNER   0x10    /* owner is a special value */
+#define FMV_OF_LAST            0x20    /* segment is the last in the FS */
+
+/*     fmv_owner special values */
+#define FMV_OWN_FREE           (-1ULL) /* free space */
+#define FMV_OWN_UNKNOWN                (-2ULL) /* unknown owner */
+#define FMV_OWN_FS             (-3ULL) /* static fs metadata */
+#define FMV_OWN_LOG            (-4ULL) /* journalling log */
+#define FMV_OWN_AG             (-5ULL) /* per-AG metadata */
+#define FMV_OWN_INOBT          (-6ULL) /* inode btree blocks */
+#define FMV_OWN_INODES         (-7ULL) /* inodes */
+#define FMV_OWN_REFC           (-8ULL) /* refcount tree */
+#define FMV_OWN_COW            (-9ULL) /* cow staging */
+#define FMV_OWN_DEFECTIVE      (-10ULL) /* bad blocks */
+
+/*
  * Structure for XFS_IOC_FSSETDM.
  * For use by backup and restore programs to set the XFS on-disk inode
  * fields di_dmevmask and di_dmstate.  These must be set to exactly and
@@ -498,6 +562,7 @@ typedef struct xfs_swapext
 #define XFS_IOC_GETBMAPX       _IOWR('X', 56, struct getbmap)
 #define XFS_IOC_ZERO_RANGE     _IOW ('X', 57, struct xfs_flock64)
 #define XFS_IOC_FREE_EOFBLOCKS _IOR ('X', 58, struct xfs_fs_eofblocks)
+#define XFS_IOC_GETFSMAP       _IOWR('X', 59, struct getfsmap)
 
 /*
  * ioctl commands that replace IRIX syssgi()'s
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 0f96847..a531f060 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -43,6 +43,7 @@
 #include "xfs_log.h"
 #include "xfs_filestream.h"
 #include "xfs_rmap.h"
+#include "xfs_bit.h"
 
 /*
  * File system operations
@@ -947,3 +948,530 @@ xfs_do_force_shutdown(
        "Please umount the filesystem and rectify the problem(s)");
        }
 }
+
+/* getfsmap query state */
+struct xfs_getfsmap_info {
+       struct getfsmap         *fmv;           /* vector header */
+       xfs_fsmap_format_t      formatter;      /* formatting fn */
+       void                    *format_arg;    /* format buffer */
+       bool                    last;           /* last extent? */
+       xfs_daddr_t             next_daddr;     /* next daddr we expect */
+       u32                     dev;            /* device id */
+
+       xfs_agnumber_t          agno;           /* AG number, if applicable */
+       struct xfs_buf          *agbp;          /* AGF, for refcount queries */
+       struct xfs_rmap_irec    low;            /* low rmap key */
+       struct xfs_rmap_irec    high;           /* high rmap key */
+};
+
+/* Associate a device with a getfsmap handler. */
+struct xfs_getfsmap_dev {
+       u32                     dev;
+       int                     (*fn)(struct xfs_mount *mp,
+                                     struct getfsmap *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;
+}
+
+/* Compare a record against our starting point */
+static bool
+xfs_getfsmap_rec_before_low_key(
+       struct xfs_getfsmap_info        *info,
+       struct xfs_rmap_irec            *rec)
+{
+       uint64_t                        x, y;
+
+       if (rec->rm_startblock < info->low.rm_startblock)
+               return true;
+       if (rec->rm_startblock > info->low.rm_startblock)
+               return false;
+
+       if (rec->rm_owner < info->low.rm_owner)
+               return true;
+       if (rec->rm_owner > info->low.rm_owner)
+               return false;
+
+       x = xfs_rmap_irec_offset_pack(rec);
+       y = xfs_rmap_irec_offset_pack(&info->low);
+       if (x < y)
+               return true;
+       return false;
+}
+
+/*
+ * Format a reverse mapping for getfsmap, having translated rm_startblock
+ * into the appropriate daddr units.
+ */
+STATIC int
+xfs_getfsmap_helper(
+       struct xfs_mount                *mp,
+       struct xfs_getfsmap_info        *info,
+       struct xfs_rmap_irec            *rec,
+       xfs_daddr_t                     rec_daddr)
+{
+       struct getfsmap                 fmv;
+       xfs_daddr_t                     key_end;
+       int                             error;
+
+       /*
+        * Filter out records that start before our startpoint, if the
+        * caller requested that.
+        */
+       if (info->fmv->fmv_length &&
+           xfs_getfsmap_rec_before_low_key(info, rec)) {
+               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 caller passed in a length with the low record and
+        * the record represents a file data extent, we incremented
+        * the offset in the low key by the length in the hopes of
+        * finding reverse mappings for the physical blocks we just
+        * saw.  We did /not/ increment next_daddr by the length
+        * because the range query would not be able to find shared
+        * extents within the same physical block range.
+        *
+        * However, the extent we've been fed could have a startblock
+        * past the passed-in low record.  If this is the case,
+        * advance next_daddr to the end of the passed-in low record
+        * so we don't report the extent prior to this extent as
+        * free.
+        */
+       key_end = info->fmv->fmv_block + info->fmv->fmv_length;
+       if (info->next_daddr < key_end && rec_daddr >= key_end)
+               info->next_daddr = key_end;
+
+       /* Are we just counting mappings? */
+       if (info->fmv->fmv_count == 2) {
+               if (rec_daddr > info->next_daddr)
+                       info->fmv->fmv_entries++;
+
+               if (info->last)
+                       return XFS_BTREE_QUERY_RANGE_CONTINUE;
+
+               info->fmv->fmv_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 some free space.  Report that too.
+        */
+       if (rec_daddr > info->next_daddr) {
+               if (info->fmv->fmv_entries >= info->fmv->fmv_count - 2)
+                       return XFS_BTREE_QUERY_RANGE_ABORT;
+
+               trace_xfs_fsmap_mapping(mp, info->agno,
+                               XFS_DADDR_TO_FSB(mp, info->next_daddr),
+                               XFS_DADDR_TO_FSB(mp, rec_daddr -
+                                               info->next_daddr),
+                               FMV_OWN_FREE, 0);
+
+               fmv.fmv_device = info->dev;
+               fmv.fmv_block = info->next_daddr;
+               fmv.fmv_owner = FMV_OWN_FREE;
+               fmv.fmv_offset = 0;
+               fmv.fmv_length = rec_daddr - info->next_daddr;
+               fmv.fmv_oflags = FMV_OF_SPECIAL_OWNER;
+               fmv.fmv_count = 0;
+               fmv.fmv_entries = 0;
+               fmv.fmv_unused1 = 0;
+               fmv.fmv_unused2 = 0;
+               error = info->formatter(&fmv, info->format_arg);
+               if (error)
+                       return error;
+               info->fmv->fmv_entries++;
+       }
+
+       if (info->last)
+               goto out;
+
+       /* Fill out the extent we found */
+       if (info->fmv->fmv_entries >= info->fmv->fmv_count - 2)
+               return XFS_BTREE_QUERY_RANGE_ABORT;
+
+       trace_xfs_fsmap_mapping(mp, info->agno,
+                       rec->rm_startblock, rec->rm_blockcount, rec->rm_owner,
+                       rec->rm_offset);
+
+       fmv.fmv_device = info->dev;
+       fmv.fmv_block = rec_daddr;
+       fmv.fmv_owner = rec->rm_owner;
+       fmv.fmv_offset = XFS_FSB_TO_BB(mp, rec->rm_offset);
+       fmv.fmv_length = XFS_FSB_TO_BB(mp, rec->rm_blockcount);
+       fmv.fmv_oflags = 0;
+       fmv.fmv_count = 0;
+       fmv.fmv_entries = 0;
+       fmv.fmv_unused1 = 0;
+       fmv.fmv_unused2 = 0;
+       if (XFS_RMAP_NON_INODE_OWNER(rec->rm_owner))
+               fmv.fmv_oflags |= FMV_OF_SPECIAL_OWNER;
+       if (rec->rm_flags & XFS_RMAP_UNWRITTEN)
+               fmv.fmv_oflags |= FMV_OF_PREALLOC;
+       if (rec->rm_flags & XFS_RMAP_ATTR_FORK)
+               fmv.fmv_oflags |= FMV_OF_ATTR_FORK;
+       if (rec->rm_flags & XFS_RMAP_BMBT_BLOCK)
+               fmv.fmv_oflags |= FMV_OF_EXTENT_MAP;
+       error = info->formatter(&fmv, info->format_arg);
+       if (error)
+               return error;
+       info->fmv->fmv_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(mp, info, rec, rec_daddr);
+}
+
+/* Transform a absolute-startblock rmap (rtdev, logdev) into a fsmap */
+STATIC int
+xfs_getfsmap_rtdev_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_daddr_t                     rec_daddr;
+
+       rec_daddr = XFS_FSB_TO_BB(mp, rec->rm_startblock);
+
+       return xfs_getfsmap_helper(mp, 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 getfsmap         *fmv)
+{
+       irec->rm_flags = 0;
+       if (fmv->fmv_oflags & FMV_OF_ATTR_FORK)
+               irec->rm_flags |= XFS_RMAP_ATTR_FORK;
+       if (fmv->fmv_oflags & FMV_OF_EXTENT_MAP)
+               irec->rm_flags |= XFS_RMAP_BMBT_BLOCK;
+       if (fmv->fmv_oflags & FMV_OF_PREALLOC)
+               irec->rm_flags |= XFS_RMAP_UNWRITTEN;
+}
+
+/* Execute a getfsmap query against the log device. */
+STATIC int
+xfs_getfsmap_logdev(
+       struct xfs_mount                *mp,
+       struct getfsmap                 *keys,
+       struct xfs_getfsmap_info        *info)
+{
+       struct xfs_btree_cur            cur;
+       struct getfsmap                 *lowkey = keys;
+       struct xfs_rmap_irec            rmap;
+
+       /* Set up search keys */
+       info->low.rm_startblock = XFS_BB_TO_FSBT(mp, lowkey->fmv_block);
+       info->low.rm_offset = XFS_BB_TO_FSBT(mp, lowkey->fmv_offset);
+       info->low.rm_owner = lowkey->fmv_owner;
+       info->low.rm_blockcount = 0;
+       xfs_getfsmap_set_irec_flags(&info->low, lowkey);
+
+       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;
+
+       trace_xfs_fsmap_low_key(mp, info->agno,
+                       info->low.rm_startblock,
+                       info->low.rm_blockcount,
+                       info->low.rm_owner,
+                       info->low.rm_offset);
+
+       trace_xfs_fsmap_high_key(mp, info->agno,
+                       info->high.rm_startblock,
+                       info->high.rm_blockcount,
+                       info->high.rm_owner,
+                       info->high.rm_offset);
+
+
+       if (lowkey->fmv_block > 0)
+               return 0;
+
+       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;
+
+       cur.bc_mp = mp;
+       return xfs_getfsmap_rtdev_helper(&cur, &rmap, info);
+}
+
+/* Execute a getfsmap query against the regular data device. */
+STATIC int
+xfs_getfsmap_datadev(
+       struct xfs_mount                *mp,
+       struct getfsmap                 *keys,
+       struct xfs_getfsmap_info        *info)
+{
+       struct xfs_btree_cur            *bt_cur = NULL;
+       struct getfsmap                 *lowkey;
+       struct getfsmap                 *highkey;
+       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;
+
+       lowkey = keys;
+       highkey = keys + 1;
+       eofs = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
+       if (lowkey->fmv_block >= eofs)
+               return 0;
+       if (highkey->fmv_block >= eofs)
+               highkey->fmv_block = eofs - 1;
+       start_fsb = XFS_DADDR_TO_FSB(mp, lowkey->fmv_block);
+       end_fsb = XFS_DADDR_TO_FSB(mp, highkey->fmv_block);
+
+       /* Set up search keys */
+       info->low.rm_startblock = XFS_FSB_TO_AGBNO(mp, start_fsb);
+       info->low.rm_offset = XFS_BB_TO_FSBT(mp, lowkey->fmv_offset);
+       info->low.rm_owner = lowkey->fmv_owner;
+       info->low.rm_blockcount = 0;
+       xfs_getfsmap_set_irec_flags(&info->low, lowkey);
+
+       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++) {
+               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,
+                                       highkey->fmv_offset);
+                       info->high.rm_owner = highkey->fmv_owner;
+                       xfs_getfsmap_set_irec_flags(&info->high, highkey);
+               }
+
+               if (bt_cur) {
+                       xfs_btree_del_cursor(bt_cur, XFS_BTREE_NOERROR);
+                       xfs_trans_brelse(NULL, info->agbp);
+                       bt_cur = NULL;
+                       info->agbp = NULL;
+               }
+
+               error = xfs_alloc_read_agf(mp, NULL, info->agno, 0,
+                               &info->agbp);
+               if (error)
+                       goto err;
+
+               trace_xfs_fsmap_low_key(mp, info->agno,
+                               info->low.rm_startblock,
+                               info->low.rm_blockcount,
+                               info->low.rm_owner,
+                               info->low.rm_offset);
+
+               trace_xfs_fsmap_high_key(mp, info->agno,
+                               info->high.rm_startblock,
+                               info->high.rm_blockcount,
+                               info->high.rm_owner,
+                               info->high.rm_offset);
+
+               bt_cur = xfs_rmapbt_init_cursor(mp, NULL, info->agbp,
+                               info->agno);
+               error = xfs_rmap_query_range(bt_cur, &info->low, &info->high,
+                               xfs_getfsmap_datadev_helper, info);
+               if (error)
+                       goto err;
+
+               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 free space at the end of the AG */
+       info->last = true;
+       error = xfs_getfsmap_datadev_helper(bt_cur, &info->high, info);
+       if (error)
+               goto err;
+
+err:
+       if (bt_cur)
+               xfs_btree_del_cursor(bt_cur, error < 0 ? XFS_BTREE_ERROR :
+                                                        XFS_BTREE_NOERROR);
+       if (info->agbp) {
+               xfs_trans_brelse(NULL, info->agbp);
+               info->agbp = NULL;
+       }
+
+       return error;
+}
+
+/* Do we recognize the device? */
+STATIC bool
+xfs_getfsmap_is_valid_device(
+       struct xfs_mount        *mp,
+       struct getfsmap         *fmv)
+{
+       if (fmv->fmv_device == 0 || fmv->fmv_device == UINT_MAX ||
+           fmv->fmv_device == new_encode_dev(mp->m_ddev_targp->bt_dev))
+               return true;
+       if (mp->m_logdev_targp &&
+           fmv->fmv_device == new_encode_dev(mp->m_logdev_targp->bt_dev))
+               return true;
+       return false;
+}
+
+#define XFS_GETFSMAP_DEVS      3
+/*
+ * Get filesystem's extents as described in fmv, and format for
+ * output.  Calls formatter to fill the user's buffer until all
+ * extents are mapped, until the passed-in fmv->fmv_count slots have
+ * been filled, or until the formatter short-circuits the loop, if it
+ * is tracking filled-in extents on its own.
+ */
+int
+xfs_getfsmap(
+       struct xfs_mount                *mp,
+       struct getfsmap                 *fmv_low,
+       xfs_fsmap_format_t              formatter,
+       void                            *arg)
+{
+       struct getfsmap                 *fmv_high;
+       struct getfsmap                 keys[2];
+       struct xfs_getfsmap_dev         handlers[XFS_GETFSMAP_DEVS];
+       struct xfs_getfsmap_info        info;
+       int                             i;
+       int                             error = 0;
+
+       if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+               return -EOPNOTSUPP;
+       if (fmv_low->fmv_count < 2)
+               return -EINVAL;
+       if (fmv_low->fmv_iflags & (~FMV_HIF_VALID))
+               return -EINVAL;
+       fmv_high = fmv_low + 1;
+       if (!xfs_getfsmap_is_valid_device(mp, fmv_low) ||
+           !xfs_getfsmap_is_valid_device(mp, fmv_high) ||
+           fmv_high->fmv_iflags || fmv_high->fmv_count ||
+           fmv_high->fmv_length || fmv_high->fmv_entries ||
+           fmv_high->fmv_unused1 || fmv_low->fmv_unused1 ||
+           fmv_high->fmv_unused2 || fmv_low->fmv_unused2)
+               return -EINVAL;
+
+       fmv_low->fmv_entries = 0;
+       fmv_low->fmv_oflags = FMV_HOF_DEV_T;
+
+       /* 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;
+       if (mp->m_logdev_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);
+
+       /*
+        * Since we allow the user to copy the last fmv item from a previous
+        * call into the low key slot, we have to advance the low key by
+        * whatever the reported length is.  If the offset field doesn't apply,
+        * move up the start block to the next extent and start over with the
+        * lowest owner/offset possible; otherwise it's file data, so move up
+        * the offset only.
+        */
+       keys[0] = *fmv_low;
+       if (keys[0].fmv_oflags & (FMV_OF_SPECIAL_OWNER | FMV_OF_EXTENT_MAP)) {
+               keys[0].fmv_block += fmv_low->fmv_length;
+               keys[0].fmv_owner = 0;
+               keys[0].fmv_offset = 0;
+       } else
+               keys[0].fmv_offset += fmv_low->fmv_length;
+       memset(keys + 1, 0xFF, sizeof(struct getfsmap));
+
+       info.fmv = fmv_low;
+       info.formatter = formatter;
+       info.format_arg = arg;
+
+       /* 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 (fmv_low->fmv_device > handlers[i].dev)
+                       continue;
+               if (fmv_high->fmv_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 == fmv_high->fmv_device)
+                       keys[1] = *fmv_high;
+               if (handlers[i].dev > fmv_low->fmv_device)
+                       memset(keys, 0, sizeof(struct getfsmap));
+
+               info.next_daddr = keys[0].fmv_block;
+               info.dev = handlers[i].dev;
+               info.last = false;
+               info.agno = NULLAGNUMBER;
+               error = handlers[i].fn(mp, keys, &info);
+               if (error)
+                       break;
+
+       }
+
+       return error;
+}
diff --git a/fs/xfs/xfs_fsops.h b/fs/xfs/xfs_fsops.h
index f32713f..53ab2d7 100644
--- a/fs/xfs/xfs_fsops.h
+++ b/fs/xfs/xfs_fsops.h
@@ -26,4 +26,10 @@ extern int xfs_reserve_blocks(xfs_mount_t *mp, __uint64_t 
*inval,
                                xfs_fsop_resblks_t *outval);
 extern int xfs_fs_goingdown(xfs_mount_t *mp, __uint32_t inflags);
 
+/* fsmap to userspace formatter - copy to user & advance pointer */
+typedef int (*xfs_fsmap_format_t)(struct getfsmap *, void *);
+
+int    xfs_getfsmap(struct xfs_mount *mp, struct getfsmap *fmv,
+               xfs_fsmap_format_t formatter, void *arg);
+
 #endif /* __XFS_FSOPS_H__ */
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 9a7c878..ecdd77b 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -41,6 +41,7 @@
 #include "xfs_trans.h"
 #include "xfs_pnfs.h"
 #include "xfs_acl.h"
+#include "xfs_btree.h"
 
 #include <linux/capability.h>
 #include <linux/dcache.h>
@@ -1532,6 +1533,76 @@ xfs_ioc_getbmapx(
        return 0;
 }
 
+struct getfsmap_info {
+       struct xfs_mount        *mp;
+       struct getfsmap __user  *data;
+       __s64                   last_flags;
+};
+
+STATIC int
+xfs_getfsmap_format(struct getfsmap *fmv, void *priv)
+{
+       struct getfsmap_info    *info = priv;
+
+       trace_xfs_getfsmap_mapping(info->mp, fmv->fmv_block,
+                       fmv->fmv_length, fmv->fmv_owner,
+                       fmv->fmv_offset, fmv->fmv_oflags);
+
+       info->last_flags = fmv->fmv_oflags;
+       if (copy_to_user(info->data, fmv, sizeof(struct getfsmap)))
+               return -EFAULT;
+
+       info->data++;
+       return 0;
+}
+
+STATIC int
+xfs_ioc_getfsmap(
+       struct xfs_inode        *ip,
+       void                    __user *arg)
+{
+       struct getfsmap_info    info;
+       struct getfsmap         fmx[2];
+       bool                    aborted = false;
+       int                     error;
+
+       if (copy_from_user(&fmx, arg, 2 * sizeof(struct getfsmap)))
+               return -EFAULT;
+
+       trace_xfs_getfsmap_low_key(ip->i_mount, fmx[0].fmv_block,
+                       fmx[0].fmv_length, fmx[0].fmv_owner,
+                       fmx[0].fmv_offset, fmx[0].fmv_oflags);
+
+       trace_xfs_getfsmap_high_key(ip->i_mount, fmx[1].fmv_block,
+                       fmx[1].fmv_length, fmx[1].fmv_owner,
+                       fmx[1].fmv_offset, fmx[1].fmv_oflags);
+
+       info.mp = ip->i_mount;
+       info.data = (__force struct getfsmap *)arg + 2;
+       error = xfs_getfsmap(ip->i_mount, fmx, xfs_getfsmap_format, &info);
+       if (error == XFS_BTREE_QUERY_RANGE_ABORT) {
+               error = 0;
+               aborted = true;
+       }
+       if (error)
+               return error;
+
+       /* If we didn't abort, set the "last" flag in the last fmx */
+       if (!aborted && fmx[0].fmv_entries) {
+               info.data--;
+               info.last_flags |= FMV_OF_LAST;
+               if (copy_to_user(&info.data->fmv_oflags, &info.last_flags,
+                               sizeof(info.last_flags)))
+                       return -EFAULT;
+       }
+
+       /* copy back header */
+       if (copy_to_user(arg, fmx, 2 * sizeof(struct getfsmap)))
+               return -EFAULT;
+
+       return 0;
+}
+
 int
 xfs_ioc_swapext(
        xfs_swapext_t   *sxp)
@@ -1712,6 +1783,11 @@ xfs_file_ioctl(
        case XFS_IOC_GETBMAPX:
                return xfs_ioc_getbmapx(ip, arg);
 
+       case XFS_IOC_GETFSMAP:
+               if (!capable(CAP_SYS_ADMIN))
+                       return -EPERM;
+               return xfs_ioc_getfsmap(ip, arg);
+
        case XFS_IOC_FD_TO_HANDLE:
        case XFS_IOC_PATH_TO_HANDLE:
        case XFS_IOC_PATH_TO_FSHANDLE: {
diff --git a/fs/xfs/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c
index 321f577..9491bc8 100644
--- a/fs/xfs/xfs_ioctl32.c
+++ b/fs/xfs/xfs_ioctl32.c
@@ -554,6 +554,7 @@ xfs_file_compat_ioctl(
        case XFS_IOC_GOINGDOWN:
        case XFS_IOC_ERROR_INJECTION:
        case XFS_IOC_ERROR_CLEARALL:
+       case XFS_IOC_GETFSMAP:
                return xfs_file_ioctl(filp, cmd, p);
 #ifndef BROKEN_X86_ALIGNMENT
        /* These are handled fine if no alignment issues */
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 551b7e2..8a42609 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -2559,6 +2559,82 @@ DEFINE_RMAPBT_EVENT(xfs_rmap_lookup_le_range_result);
 DEFINE_RMAPBT_EVENT(xfs_rmap_find_right_neighbor_result);
 DEFINE_RMAPBT_EVENT(xfs_rmap_find_left_neighbor_result);
 
+/* fsmap traces */
+DECLARE_EVENT_CLASS(xfs_fsmap_class,
+       TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, xfs_fsblock_t bno,
+                xfs_filblks_t len, __uint64_t owner, __uint64_t offset),
+       TP_ARGS(mp, agno, bno, len, owner, offset),
+       TP_STRUCT__entry(
+               __field(dev_t, dev)
+               __field(xfs_agnumber_t, agno)
+               __field(xfs_fsblock_t, bno)
+               __field(xfs_filblks_t, len)
+               __field(__uint64_t, owner)
+               __field(__uint64_t, offset)
+       ),
+       TP_fast_assign(
+               __entry->dev = mp->m_super->s_dev;
+               __entry->agno = agno;
+               __entry->bno = bno;
+               __entry->len = len;
+               __entry->owner = owner;
+               __entry->offset = offset;
+       ),
+       TP_printk("dev %d:%d agno %u bno %llu len %llu owner %lld offset 
0x%llx\n",
+                 MAJOR(__entry->dev), MINOR(__entry->dev),
+                 __entry->agno,
+                 __entry->bno,
+                 __entry->len,
+                 __entry->owner,
+                 __entry->offset)
+)
+#define DEFINE_FSMAP_EVENT(name) \
+DEFINE_EVENT(xfs_fsmap_class, name, \
+       TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, \
+                xfs_fsblock_t bno, xfs_filblks_t len, __uint64_t owner, \
+                __uint64_t offset), \
+       TP_ARGS(mp, agno, bno, len, owner, offset))
+DEFINE_FSMAP_EVENT(xfs_fsmap_low_key);
+DEFINE_FSMAP_EVENT(xfs_fsmap_high_key);
+DEFINE_FSMAP_EVENT(xfs_fsmap_mapping);
+
+DECLARE_EVENT_CLASS(xfs_getfsmap_class,
+       TP_PROTO(struct xfs_mount *mp, xfs_daddr_t block, xfs_daddr_t len,
+                __uint64_t owner, __uint64_t offset, __uint64_t flags),
+       TP_ARGS(mp, block, len, owner, offset, flags),
+       TP_STRUCT__entry(
+               __field(dev_t, dev)
+               __field(xfs_daddr_t, block)
+               __field(xfs_daddr_t, len)
+               __field(__uint64_t, owner)
+               __field(__uint64_t, offset)
+               __field(__uint64_t, flags)
+       ),
+       TP_fast_assign(
+               __entry->dev = mp->m_super->s_dev;
+               __entry->block = block;
+               __entry->len = len;
+               __entry->owner = owner;
+               __entry->offset = offset;
+               __entry->flags = flags;
+       ),
+       TP_printk("dev %d:%d block %llu len %llu owner %lld offset %llu flags 
0x%llx\n",
+                 MAJOR(__entry->dev), MINOR(__entry->dev),
+                 __entry->block,
+                 __entry->len,
+                 __entry->owner,
+                 __entry->offset,
+                 __entry->flags)
+)
+#define DEFINE_GETFSMAP_EVENT(name) \
+DEFINE_EVENT(xfs_getfsmap_class, name, \
+       TP_PROTO(struct xfs_mount *mp, xfs_daddr_t block, xfs_daddr_t len, \
+                __uint64_t owner, __uint64_t offset, __uint64_t flags), \
+       TP_ARGS(mp, block, len, owner, offset, flags))
+DEFINE_GETFSMAP_EVENT(xfs_getfsmap_low_key);
+DEFINE_GETFSMAP_EVENT(xfs_getfsmap_high_key);
+DEFINE_GETFSMAP_EVENT(xfs_getfsmap_mapping);
+
 #endif /* _TRACE_XFS_H */
 
 #undef TRACE_INCLUDE_PATH

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