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@xxxxxxxxxx>
---
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).
v3: don't call the function that reports the journalling log rmap if
we don't have an external device, since the regular rmapbt will take
care of that.
v4: make it easy to plug in different implementations so that we can
query the realtime rmapbt or use the bnobt (if there's no rmapbt) to
map at least the free space.
---
fs/xfs/Makefile | 1
fs/xfs/libxfs/xfs_fs.h | 95 +++++++
fs/xfs/xfs_fsmap.c | 698 ++++++++++++++++++++++++++++++++++++++++++++++++
fs/xfs/xfs_fsmap.h | 51 ++++
fs/xfs/xfs_ioctl.c | 104 +++++++
fs/xfs/xfs_ioctl32.c | 1
fs/xfs/xfs_trace.h | 85 ++++++
fs/xfs/xfs_trans.c | 22 ++
fs/xfs/xfs_trans.h | 2
9 files changed, 1059 insertions(+)
create mode 100644 fs/xfs/xfs_fsmap.c
create mode 100644 fs/xfs/xfs_fsmap.h
diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index c7515d4..0e7ee30 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -80,6 +80,7 @@ xfs-y += xfs_aops.o \
xfs_extent_busy.o \
xfs_file.o \
xfs_filestream.o \
+ xfs_fsmap.o \
xfs_fsops.o \
xfs_globals.o \
xfs_icache.o \
diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index b72dc82..e62996f 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -93,6 +93,100 @@ struct getbmapx {
#define BMV_OF_SHARED 0x8 /* segment shared with another file */
/*
+ * Structure for XFS_IOC_GETFSMAP.
+ *
+ * The memory layout for this call are the scalar values defined in
+ * struct fsmap_head, followed by two struct fsmap that describe
+ * the lower and upper bound of mappings to return, followed by an
+ * array of struct fsmap mappings.
+ *
+ * fmh_iflags control the output of the call, whereas fmh_oflags report
+ * on the overall record output. fmh_count should be set to the
+ * length of the fmh_recs array, and fmh_entries will be set to the
+ * number of entries filled out during each call. If fmh_count is
+ * zero, the number of reverse mappings will be returned in
+ * fmh_entries, though no mappings will be returned. fmh_reserved
+ * must be set to zero.
+ *
+ * The two elements in the fmh_keys array are used to constrain the
+ * output. The first element in the array should represent the
+ * lowest disk mapping ("low key") that the user wants to learn
+ * about. If this value is all zeroes, the filesystem will return
+ * the first entry it knows about. For a subsequent call, the
+ * contents of fsmap_head.fmh_recs[fsmap_head.fmh_count - 1] should be
+ * copied into fmh_keys[0] to have the kernel start where it left off.
+ *
+ * The second element in the fmh_keys array should represent the
+ * highest disk mapping ("high key") that the user wants to learn
+ * about. If this value is all ones, the filesystem will not stop
+ * until it runs out of mapping to return or runs out of space in
+ * fmh_recs.
+ *
+ * fmr_device can be either a 32-bit cookie representing a device, or
+ * a 32-bit dev_t if the FMH_OF_DEV_T flag is set. fmr_physical,
+ * fmr_offset, and fmr_length are expressed in units of bytes.
+ * fmr_owner is either an inode number, or a special value if
+ * FMR_OF_SPECIAL_OWNER is set in fmr_flags.
+ */
+#ifndef HAVE_GETFSMAP
+struct fsmap {
+ __u32 fmr_device; /* device id */
+ __u32 fmr_flags; /* mapping flags */
+ __u64 fmr_physical; /* device offset of segment */
+ __u64 fmr_owner; /* owner id */
+ __u64 fmr_offset; /* file offset of segment */
+ __u64 fmr_length; /* length of segment */
+ __u64 fmr_reserved[3]; /* must be zero */
+};
+
+struct fsmap_head {
+ __u32 fmh_iflags; /* control flags */
+ __u32 fmh_oflags; /* output flags */
+ __u32 fmh_count; /* # of entries in array incl. input */
+ __u32 fmh_entries; /* # of entries filled in (output). */
+ __u64 fmh_reserved[6]; /* must be zero */
+
+ struct fsmap fmh_keys[2]; /* low and high keys for the mapping search */
+ struct fsmap fmh_recs[]; /* returned records */
+};
+
+/* Size of an fsmap_head with room for nr records. */
+static inline size_t
+fsmap_sizeof(
+ unsigned int nr)
+{
+ return sizeof(struct fsmap_head) + nr * sizeof(struct fsmap);
+}
+#endif
+
+/* fmh_iflags values - set by XFS_IOC_GETFSMAP caller in the header. */
+/* no flags defined yet */
+#define FMH_IF_VALID 0
+
+/* fmh_oflags values - returned in the header segment only. */
+#define FMH_OF_DEV_T 0x1 /* fmr_device values will be dev_t */
+
+/* fmr_flags values - returned for each non-header segment */
+#define FMR_OF_PREALLOC 0x1 /* segment = unwritten pre-allocation */
+#define FMR_OF_ATTR_FORK 0x2 /* segment = attribute fork */
+#define FMR_OF_EXTENT_MAP 0x4 /* segment = extent map */
+#define FMR_OF_SHARED 0x8 /* segment = shared with another file */
+#define FMR_OF_SPECIAL_OWNER 0x10 /* owner is a special value */
+#define FMR_OF_LAST 0x20 /* segment is the last in the FS */
+
+/* fmr_owner special values */
+#define FMR_OWN_FREE (-1ULL) /* free space */
+#define FMR_OWN_UNKNOWN (-2ULL) /* unknown owner */
+#define FMR_OWN_FS (-3ULL) /* static fs metadata */
+#define FMR_OWN_LOG (-4ULL) /* journalling log */
+#define FMR_OWN_AG (-5ULL) /* per-AG metadata */
+#define FMR_OWN_INOBT (-6ULL) /* inode btree blocks */
+#define FMR_OWN_INODES (-7ULL) /* inodes */
+#define FMR_OWN_REFC (-8ULL) /* refcount tree */
+#define FMR_OWN_COW (-9ULL) /* cow staging */
+#define FMR_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
@@ -502,6 +596,7 @@ 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 fsmap_head)
/*
* ioctl commands that replace IRIX syssgi()'s
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
new file mode 100644
index 0000000..019cd55
--- /dev/null
+++ b/fs/xfs/xfs_fsmap.c
@@ -0,0 +1,698 @@
+/*
+ * Copyright (C) 2016 Oracle. All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
+ *
+ * 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 "xfs_fsmap.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_fsmap *fmr,
+ struct xfs_rmap_irec *rm)
+{
+ if (!(fmr->fmr_flags & FMR_OF_SPECIAL_OWNER)) {
+ if (XFS_RMAP_NON_INODE_OWNER(fmr->fmr_owner))
+ return -EINVAL;
+ rm->rm_owner = fmr->fmr_owner;
+ return 0;
+ }
+
+ switch (fmr->fmr_owner) {
+ case 0: /* "lowest owner id possible" */
+ case FMR_OWN_FREE:
+ case FMR_OWN_UNKNOWN:
+ case FMR_OWN_FS:
+ case FMR_OWN_LOG:
+ case FMR_OWN_AG:
+ case FMR_OWN_INOBT:
+ case FMR_OWN_INODES:
+ case FMR_OWN_REFC:
+ case FMR_OWN_COW:
+ rm->rm_owner = fmr->fmr_owner;
+ return 0;
+ case FMR_OWN_DEFECTIVE:
+ /* fall through */
+ default:
+ return -EINVAL;
+ }
+}
+
+/* Convert an rmapbt owner into an fsmap owner. */
+static int
+xfs_fsmap_owner_from_rmap(
+ struct xfs_rmap_irec *rm,
+ struct xfs_fsmap *fmr)
+{
+ fmr->fmr_flags = 0;
+ if (!XFS_RMAP_NON_INODE_OWNER(rm->rm_owner)) {
+ fmr->fmr_owner = rm->rm_owner;
+ return 0;
+ }
+ fmr->fmr_flags |= FMR_OF_SPECIAL_OWNER;
+
+ switch (rm->rm_owner) {
+ case XFS_RMAP_OWN_FS:
+ case XFS_RMAP_OWN_LOG:
+ case XFS_RMAP_OWN_AG:
+ case XFS_RMAP_OWN_INOBT:
+ case XFS_RMAP_OWN_INODES:
+ case XFS_RMAP_OWN_REFC:
+ case XFS_RMAP_OWN_COW:
+ fmr->fmr_owner = rm->rm_owner;
+ return 0;
+ default:
+ return -EFSCORRUPTED;
+ }
+}
+
+/* getfsmap query state */
+struct xfs_getfsmap_info {
+ struct xfs_fsmap_head *head;
+ struct xfs_fsmap *rkey_low; /* lowest key */
+ 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 */
+ u64 missing_owner; /* owner of holes */
+
+ xfs_agnumber_t agno; /* AG number, if applicable */
+ struct xfs_buf *agf_bp; /* 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_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;
+}
+
+/* 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 xfs_fsmap fmr;
+ xfs_daddr_t key_end;
+ int error;
+
+ /*
+ * Filter out records that start before our startpoint, if the
+ * caller requested that.
+ */
+ if (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->rkey_low->fmr_physical + info->rkey_low->fmr_length;
+ if (info->dev == info->rkey_low->fmr_device &&
+ info->next_daddr < key_end && rec_daddr >= key_end)
+ info->next_daddr = key_end;
+
+ /* 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 some free space. Report that too.
+ */
+ if (rec_daddr > info->next_daddr) {
+ if (info->head->fmh_entries >= info->head->fmh_count)
+ return XFS_BTREE_QUERY_RANGE_ABORT;
+
+ trace_xfs_fsmap_mapping(mp, info->dev, info->agno,
+ XFS_DADDR_TO_FSB(mp, info->next_daddr),
+ XFS_DADDR_TO_FSB(mp, rec_daddr -
+ info->next_daddr),
+ info->missing_owner, 0);
+
+ 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->rm_startblock, rec->rm_blockcount, rec->rm_owner,
+ rec->rm_offset);
+
+ fmr.fmr_device = info->dev;
+ fmr.fmr_physical = rec_daddr;
+ error = xfs_fsmap_owner_from_rmap(rec, &fmr);
+ 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;
+ 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(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 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_fsmap *dkey_low = keys;
+ struct xfs_btree_cur cur;
+ struct xfs_rmap_irec rmap;
+ int error;
+
+ /* Set up search keys */
+ info->low.rm_startblock = XFS_BB_TO_FSBT(mp, dkey_low->fmr_physical);
+ info->low.rm_offset = XFS_BB_TO_FSBT(mp, dkey_low->fmr_offset);
+ error = xfs_fsmap_owner_to_rmap(keys, &info->low);
+ if (error)
+ return error;
+ info->low.rm_blockcount = 0;
+ xfs_getfsmap_set_irec_flags(&info->low, dkey_low);
+
+ error = xfs_fsmap_owner_to_rmap(keys + 1, &info->high);
+ 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 = FMR_OWN_FREE;
+
+ trace_xfs_fsmap_low_key(mp, info->dev, 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->dev, info->agno,
+ info->high.rm_startblock,
+ info->high.rm_blockcount,
+ info->high.rm_owner,
+ info->high.rm_offset);
+
+
+ if (dkey_low->fmr_physical > 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_trans *tp,
+ struct xfs_fsmap *keys,
+ struct xfs_getfsmap_info *info)
+{
+ struct xfs_mount *mp = tp->t_mountp;
+ struct xfs_btree_cur *bt_cur = NULL;
+ struct xfs_fsmap *dkey_low;
+ struct xfs_fsmap *dkey_high;
+ 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;
+
+ dkey_low = keys;
+ dkey_high = keys + 1;
+ eofs = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
+ if (dkey_low->fmr_physical >= eofs)
+ return 0;
+ if (dkey_high->fmr_physical >= eofs)
+ dkey_high->fmr_physical = eofs - 1;
+ start_fsb = XFS_DADDR_TO_FSB(mp, dkey_low->fmr_physical);
+ end_fsb = XFS_DADDR_TO_FSB(mp, dkey_high->fmr_physical);
+
+ /* Set up search keys */
+ info->low.rm_startblock = XFS_FSB_TO_AGBNO(mp, start_fsb);
+ info->low.rm_offset = XFS_BB_TO_FSBT(mp, dkey_low->fmr_offset);
+ error = xfs_fsmap_owner_to_rmap(dkey_low, &info->low);
+ if (error)
+ return error;
+ info->low.rm_blockcount = 0;
+ xfs_getfsmap_set_irec_flags(&info->low, dkey_low);
+
+ 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 = FMR_OWN_FREE;
+
+ 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,
+ dkey_high->fmr_offset);
+ error = xfs_fsmap_owner_to_rmap(dkey_high, &info->high);
+ if (error)
+ goto err;
+ xfs_getfsmap_set_irec_flags(&info->high, dkey_high);
+ }
+
+ if (bt_cur) {
+ xfs_btree_del_cursor(bt_cur, XFS_BTREE_NOERROR);
+ bt_cur = NULL;
+ 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.rm_startblock,
+ info->low.rm_blockcount,
+ info->low.rm_owner,
+ info->low.rm_offset);
+
+ trace_xfs_fsmap_high_key(mp, info->dev, 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, tp, info->agf_bp,
+ 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->agf_bp)
+ info->agf_bp = NULL;
+
+ return error;
+}
+
+/* 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 3
+/*
+ * 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.
+ */
+int
+xfs_getfsmap(
+ struct xfs_mount *mp,
+ struct xfs_fsmap_head *head,
+ xfs_fsmap_format_t formatter,
+ void *arg)
+{
+ struct xfs_trans *tp;
+ struct xfs_fsmap *rkey_low; /* request keys */
+ struct xfs_fsmap *rkey_high;
+ 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;
+ rkey_low = head->fmh_keys;
+ rkey_high = rkey_low + 1;
+ if (!xfs_getfsmap_is_valid_device(mp, rkey_low) ||
+ !xfs_getfsmap_is_valid_device(mp, rkey_high))
+ 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;
+ 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);
+
+ /*
+ * Since we allow the user to copy the last mapping 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.
+ */
+ dkeys[0] = *rkey_low;
+ 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;
+ dkeys[0].fmr_offset = 0;
+ } else
+ dkeys[0].fmr_offset += dkeys[0].fmr_length;
+ memset(&dkeys[1], 0xFF, sizeof(struct xfs_fsmap));
+
+ if (!xfs_getfsmap_check_keys(dkeys, rkey_high))
+ return -EINVAL;
+
+ info.rkey_low = rkey_low;
+ 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 (rkey_low->fmr_device > handlers[i].dev)
+ continue;
+ if (rkey_high->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 == rkey_high->fmr_device)
+ dkeys[1] = *rkey_high;
+ if (handlers[i].dev > rkey_low->fmr_device)
+ memset(&dkeys[0], 0, sizeof(struct xfs_fsmap));
+
+ error = xfs_trans_alloc_empty(mp, &tp);
+ if (error)
+ break;
+
+ info.next_daddr = dkeys[0].fmr_physical;
+ 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;
+ }
+
+ if (tp)
+ xfs_trans_cancel(tp);
+ head->fmh_oflags = FMH_OF_DEV_T;
+ return error;
+}
diff --git a/fs/xfs/xfs_fsmap.h b/fs/xfs/xfs_fsmap.h
new file mode 100644
index 0000000..ebc8fd2
--- /dev/null
+++ b/fs/xfs/xfs_fsmap.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2016 Oracle. All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
+ *
+ * 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.
+ */
+#ifndef __XFS_FSMAP_H__
+#define __XFS_FSMAP_H__
+
+/* internal fsmap representation */
+struct xfs_fsmap {
+ dev_t fmr_device; /* device id */
+ uint32_t fmr_flags; /* mapping flags */
+ uint64_t fmr_physical; /* device offset of segment */
+ uint64_t fmr_owner; /* owner id */
+ xfs_fileoff_t fmr_offset; /* file offset of segment */
+ xfs_filblks_t fmr_length; /* length of segment, blocks */
+};
+
+struct xfs_fsmap_head {
+ uint32_t fmh_iflags; /* control flags */
+ uint32_t fmh_oflags; /* output flags */
+ unsigned int fmh_count; /* # of entries in array incl. input */
+ unsigned int fmh_entries; /* # of entries filled in (output). */
+
+ struct xfs_fsmap fmh_keys[2]; /* low and high keys */
+};
+
+void xfs_fsmap_from_internal(struct fsmap *dest, struct xfs_fsmap *src);
+void xfs_fsmap_to_internal(struct xfs_fsmap *dest, struct fsmap *src);
+
+/* fsmap to userspace formatter - copy to user & advance pointer */
+typedef int (*xfs_fsmap_format_t)(struct xfs_fsmap *, void *);
+
+int xfs_getfsmap(struct xfs_mount *mp, struct xfs_fsmap_head *head,
+ xfs_fsmap_format_t formatter, void *arg);
+
+#endif /* __XFS_FSMAP_H__ */
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index c245bed..ad49e2c 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -41,6 +41,8 @@
#include "xfs_trans.h"
#include "xfs_pnfs.h"
#include "xfs_acl.h"
+#include "xfs_btree.h"
+#include "xfs_fsmap.h"
#include <linux/capability.h>
#include <linux/dcache.h>
@@ -1609,6 +1611,103 @@ xfs_ioc_getbmapx(
return 0;
}
+struct getfsmap_info {
+ struct xfs_mount *mp;
+ struct fsmap __user *data;
+ __u32 last_flags;
+};
+
+STATIC int
+xfs_getfsmap_format(struct xfs_fsmap *xfm, void *priv)
+{
+ struct getfsmap_info *info = priv;
+ struct fsmap fm;
+
+ trace_xfs_getfsmap_mapping(info->mp, xfm->fmr_device, xfm->fmr_physical,
+ xfm->fmr_length, xfm->fmr_owner, xfm->fmr_offset,
+ xfm->fmr_flags);
+
+ info->last_flags = xfm->fmr_flags;
+ xfs_fsmap_from_internal(&fm, xfm);
+ if (copy_to_user(info->data, &fm, sizeof(struct fsmap)))
+ return -EFAULT;
+
+ info->data++;
+ return 0;
+}
+
+STATIC int
+xfs_ioc_getfsmap(
+ struct xfs_inode *ip,
+ void __user *arg)
+{
+ struct getfsmap_info info;
+ struct xfs_fsmap_head xhead = {0};
+ struct fsmap_head head;
+ bool aborted = false;
+ int error;
+
+ if (copy_from_user(&head, arg, sizeof(struct fsmap_head)))
+ return -EFAULT;
+ if (head.fmh_reserved[0] || head.fmh_reserved[1] ||
+ head.fmh_reserved[2] || head.fmh_reserved[3] ||
+ head.fmh_reserved[4] || head.fmh_reserved[5] ||
+ head.fmh_keys[0].fmr_reserved[0] ||
+ head.fmh_keys[0].fmr_reserved[1] ||
+ head.fmh_keys[0].fmr_reserved[2] ||
+ head.fmh_keys[1].fmr_reserved[0] ||
+ head.fmh_keys[1].fmr_reserved[1] ||
+ head.fmh_keys[1].fmr_reserved[2])
+ return -EINVAL;
+
+ xhead.fmh_iflags = head.fmh_iflags;
+ xhead.fmh_count = head.fmh_count;
+ xfs_fsmap_to_internal(&xhead.fmh_keys[0], &head.fmh_keys[0]);
+ xfs_fsmap_to_internal(&xhead.fmh_keys[1], &head.fmh_keys[1]);
+
+ trace_xfs_getfsmap_low_key(ip->i_mount,
+ xhead.fmh_keys[0].fmr_device,
+ xhead.fmh_keys[0].fmr_physical,
+ xhead.fmh_keys[0].fmr_length,
+ xhead.fmh_keys[0].fmr_owner,
+ xhead.fmh_keys[0].fmr_offset,
+ xhead.fmh_keys[0].fmr_flags);
+
+ trace_xfs_getfsmap_high_key(ip->i_mount,
+ xhead.fmh_keys[1].fmr_device,
+ xhead.fmh_keys[1].fmr_physical,
+ xhead.fmh_keys[1].fmr_length,
+ xhead.fmh_keys[1].fmr_owner,
+ xhead.fmh_keys[1].fmr_offset,
+ xhead.fmh_keys[1].fmr_flags);
+
+ info.mp = ip->i_mount;
+ info.data = ((__force struct fsmap_head *)arg)->fmh_recs;
+ error = xfs_getfsmap(ip->i_mount, &xhead, xfs_getfsmap_format, &info);
+ if (error == XFS_BTREE_QUERY_RANGE_ABORT) {
+ error = 0;
+ aborted = true;
+ } else if (error)
+ return error;
+
+ /* If we didn't abort, set the "last" flag in the last fmx */
+ if (!aborted && xhead.fmh_entries) {
+ info.data--;
+ info.last_flags |= FMR_OF_LAST;
+ if (copy_to_user(&info.data->fmr_flags, &info.last_flags,
+ sizeof(info.last_flags)))
+ return -EFAULT;
+ }
+
+ /* copy back header */
+ head.fmh_entries = xhead.fmh_entries;
+ head.fmh_oflags = xhead.fmh_oflags;
+ if (copy_to_user(arg, &head, sizeof(struct fsmap_head)))
+ return -EFAULT;
+
+ return 0;
+}
+
int
xfs_ioc_swapext(
xfs_swapext_t *sxp)
@@ -1789,6 +1888,11 @@ 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 0907752..71778d0 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -3375,6 +3375,91 @@ DEFINE_INODE_IREC_EVENT(xfs_swap_extent_rmap_remap);
DEFINE_INODE_IREC_EVENT(xfs_swap_extent_rmap_remap_piece);
DEFINE_INODE_ERROR_EVENT(xfs_swap_extent_rmap_error);
+/* fsmap traces */
+DECLARE_EVENT_CLASS(xfs_fsmap_class,
+ TP_PROTO(struct xfs_mount *mp, u32 keydev, xfs_agnumber_t agno,
+ xfs_fsblock_t bno, xfs_filblks_t len, __uint64_t owner,
+ __uint64_t offset),
+ TP_ARGS(mp, keydev, agno, bno, len, owner, offset),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(dev_t, keydev)
+ __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->keydev = new_decode_dev(keydev);
+ __entry->agno = agno;
+ __entry->bno = bno;
+ __entry->len = len;
+ __entry->owner = owner;
+ __entry->offset = offset;
+ ),
+ TP_printk("dev %d:%d keydev %d:%d agno %u bno %llu len %llu owner %lld offset 0x%llx\n",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ MAJOR(__entry->keydev), MINOR(__entry->keydev),
+ __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, u32 keydev, xfs_agnumber_t agno, \
+ xfs_fsblock_t bno, xfs_filblks_t len, __uint64_t owner, \
+ __uint64_t offset), \
+ TP_ARGS(mp, keydev, 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, u32 keydev, xfs_daddr_t block,
+ xfs_daddr_t len, __uint64_t owner, __uint64_t offset,
+ __uint64_t flags),
+ TP_ARGS(mp, keydev, block, len, owner, offset, flags),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(dev_t, keydev)
+ __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->keydev = new_decode_dev(keydev);
+ __entry->block = block;
+ __entry->len = len;
+ __entry->owner = owner;
+ __entry->offset = offset;
+ __entry->flags = flags;
+ ),
+ TP_printk("dev %d:%d keydev %d:%d block %llu len %llu owner %lld offset %llu flags 0x%llx\n",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ MAJOR(__entry->keydev), MINOR(__entry->keydev),
+ __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, u32 keydev, xfs_daddr_t block, \
+ xfs_daddr_t len, __uint64_t owner, __uint64_t offset, \
+ __uint64_t flags), \
+ TP_ARGS(mp, keydev, 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
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 70f42ea..a280e12 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -263,6 +263,28 @@ xfs_trans_alloc(
}
/*
+ * Create an empty transaction with no reservation. This is a defensive
+ * mechanism for routines that query metadata without actually modifying
+ * them -- if the metadata being queried is somehow cross-linked (think a
+ * btree block pointer that points higher in the tree), we risk deadlock.
+ * However, blocks grabbed as part of a transaction can be re-grabbed.
+ * The verifiers will notice the corrupt block and the operation will fail
+ * back to userspace without deadlocking.
+ *
+ * Note the zero-length reservation; this transaction MUST be cancelled
+ * without any dirty data.
+ */
+int
+xfs_trans_alloc_empty(
+ struct xfs_mount *mp,
+ struct xfs_trans **tpp)
+{
+ struct xfs_trans_res resv = {0};
+
+ return xfs_trans_alloc(mp, &resv, 0, 0, XFS_TRANS_NO_WRITECOUNT, tpp);
+}
+
+/*
* Record the indicated change to the given field for application
* to the file system's superblock when the transaction commits.
* For now, just store the change in the transaction structure.
diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h
index 61b7fbd..98024cb 100644
--- a/fs/xfs/xfs_trans.h
+++ b/fs/xfs/xfs_trans.h
@@ -159,6 +159,8 @@ typedef struct xfs_trans {
int xfs_trans_alloc(struct xfs_mount *mp, struct xfs_trans_res *resp,
uint blocks, uint rtextents, uint flags,
struct xfs_trans **tpp);
+int xfs_trans_alloc_empty(struct xfs_mount *mp,
+ struct xfs_trans **tpp);
void xfs_trans_mod_sb(xfs_trans_t *, uint, int64_t);
struct xfs_buf *xfs_trans_get_buf_map(struct xfs_trans *tp,
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