xfs: rewrite getbmap using the xfs_iext_* helpers
Currently getbmap uses xfs_bmapi_read to query the extent map, and then
fixes up various bits that are eventually reported to userspace.
This patch instead rewrites it to use xfs_iext_lookup_extent and
xfs_iext_get_extent to iteratively process the extent map. This not
only avoids the need to allocate a map for the returned xfs_bmbt_irec
structures but also greatly simplified the code.
There are two intentional behavior changes compared to the old code:
- the current code reports unwritten extents that don't directly border
a written one as unwritten even when not passing the BMV_IF_PREALLOC
option, contrary to the documentation. The new code requires the
BMV_IF_PREALLOC flag to report the unwrittent extent bit.
- The new code does never merges consecutive extents, unlike the old
code that sometimes does it based on the boundaries of the
xfs_bmapi_read calls. Note that the extent merging behavior was
entirely undocumented.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 6503cfa..2564b8b 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -405,127 +405,105 @@
return 0;
}
-/*
- * returns 1 for success, 0 if we failed to map the extent.
- */
-STATIC int
-xfs_getbmapx_fix_eof_hole(
- xfs_inode_t *ip, /* xfs incore inode pointer */
- int whichfork,
- struct getbmapx *out, /* output structure */
- int prealloced, /* this is a file with
- * preallocated data space */
- int64_t end, /* last block requested */
- xfs_fsblock_t startblock,
- bool moretocome)
+static int
+xfs_getbmap_report_one(
+ struct xfs_inode *ip,
+ struct getbmapx *bmv,
+ struct getbmapx *out,
+ int64_t bmv_end,
+ struct xfs_bmbt_irec *got)
{
- int64_t fixlen;
- xfs_mount_t *mp; /* file system mount point */
- xfs_ifork_t *ifp; /* inode fork pointer */
- xfs_extnum_t lastx; /* last extent pointer */
- xfs_fileoff_t fileblock;
+ struct getbmapx *p = out + bmv->bmv_entries;
+ bool shared = false, trimmed = false;
+ int error;
- if (startblock == HOLESTARTBLOCK) {
- mp = ip->i_mount;
- out->bmv_block = -1;
- fixlen = XFS_FSB_TO_BB(mp, XFS_B_TO_FSB(mp, XFS_ISIZE(ip)));
- fixlen -= out->bmv_offset;
- if (prealloced && out->bmv_offset + out->bmv_length == end) {
- /* Came to hole at EOF. Trim it. */
- if (fixlen <= 0)
- return 0;
- out->bmv_length = fixlen;
- }
- } else {
- if (startblock == DELAYSTARTBLOCK)
- out->bmv_block = -2;
- else
- out->bmv_block = xfs_fsb_to_db(ip, startblock);
- fileblock = XFS_BB_TO_FSB(ip->i_mount, out->bmv_offset);
- ifp = XFS_IFORK_PTR(ip, whichfork);
- if (!moretocome &&
- xfs_iext_bno_to_ext(ifp, fileblock, &lastx) &&
- (lastx == xfs_iext_count(ifp) - 1))
- out->bmv_oflags |= BMV_OF_LAST;
- }
-
- return 1;
-}
-
-/* Adjust the reported bmap around shared/unshared extent transitions. */
-STATIC int
-xfs_getbmap_adjust_shared(
- struct xfs_inode *ip,
- int whichfork,
- struct xfs_bmbt_irec *map,
- struct getbmapx *out,
- struct xfs_bmbt_irec *next_map)
-{
- struct xfs_mount *mp = ip->i_mount;
- xfs_agnumber_t agno;
- xfs_agblock_t agbno;
- xfs_agblock_t ebno;
- xfs_extlen_t elen;
- xfs_extlen_t nlen;
- int error;
-
- next_map->br_startblock = NULLFSBLOCK;
- next_map->br_startoff = NULLFILEOFF;
- next_map->br_blockcount = 0;
-
- /* Only written data blocks can be shared. */
- if (!xfs_is_reflink_inode(ip) ||
- whichfork != XFS_DATA_FORK ||
- !xfs_bmap_is_real_extent(map))
- return 0;
-
- agno = XFS_FSB_TO_AGNO(mp, map->br_startblock);
- agbno = XFS_FSB_TO_AGBNO(mp, map->br_startblock);
- error = xfs_reflink_find_shared(mp, NULL, agno, agbno,
- map->br_blockcount, &ebno, &elen, true);
+ error = xfs_reflink_trim_around_shared(ip, got, &shared, &trimmed);
if (error)
return error;
- if (ebno == NULLAGBLOCK) {
- /* No shared blocks at all. */
- return 0;
- } else if (agbno == ebno) {
+ if (isnullstartblock(got->br_startblock) ||
+ got->br_startblock == DELAYSTARTBLOCK) {
/*
- * Shared extent at (agbno, elen). Shrink the reported
- * extent length and prepare to move the start of map[i]
- * to agbno+elen, with the aim of (re)formatting the new
- * map[i] the next time through the inner loop.
+ * Delalloc extents that start beyond EOF can occur due to
+ * speculative EOF allocation when the delalloc extent is larger
+ * than the largest freespace extent at conversion time. These
+ * extents cannot be converted by data writeback, so can exist
+ * here even if we are not supposed to be finding delalloc
+ * extents.
*/
- out->bmv_length = XFS_FSB_TO_BB(mp, elen);
- out->bmv_oflags |= BMV_OF_SHARED;
- if (elen != map->br_blockcount) {
- *next_map = *map;
- next_map->br_startblock += elen;
- next_map->br_startoff += elen;
- next_map->br_blockcount -= elen;
- }
- map->br_blockcount -= elen;
+ if (got->br_startoff < XFS_B_TO_FSB(ip->i_mount, XFS_ISIZE(ip)))
+ ASSERT((bmv->bmv_iflags & BMV_IF_DELALLOC) != 0);
+
+ p->bmv_oflags |= BMV_OF_DELALLOC;
+ p->bmv_block = -2;
} else {
- /*
- * There's an unshared extent (agbno, ebno - agbno)
- * followed by shared extent at (ebno, elen). Shrink
- * the reported extent length to cover only the unshared
- * extent and prepare to move up the start of map[i] to
- * ebno, with the aim of (re)formatting the new map[i]
- * the next time through the inner loop.
- */
- *next_map = *map;
- nlen = ebno - agbno;
- out->bmv_length = XFS_FSB_TO_BB(mp, nlen);
- next_map->br_startblock += nlen;
- next_map->br_startoff += nlen;
- next_map->br_blockcount -= nlen;
- map->br_blockcount -= nlen;
+ p->bmv_block = xfs_fsb_to_db(ip, got->br_startblock);
}
+ if (got->br_state == XFS_EXT_UNWRITTEN &&
+ (bmv->bmv_iflags & BMV_IF_PREALLOC))
+ p->bmv_oflags |= BMV_OF_PREALLOC;
+
+ if (shared)
+ p->bmv_oflags |= BMV_OF_SHARED;
+
+ p->bmv_offset = XFS_FSB_TO_BB(ip->i_mount, got->br_startoff);
+ p->bmv_length = XFS_FSB_TO_BB(ip->i_mount, got->br_blockcount);
+
+ bmv->bmv_offset = p->bmv_offset + p->bmv_length;
+ bmv->bmv_length = max(0LL, bmv_end - bmv->bmv_offset);
+ bmv->bmv_entries++;
return 0;
}
+static void
+xfs_getbmap_report_hole(
+ struct xfs_inode *ip,
+ struct getbmapx *bmv,
+ struct getbmapx *out,
+ int64_t bmv_end,
+ xfs_fileoff_t bno,
+ xfs_fileoff_t end)
+{
+ struct getbmapx *p = out + bmv->bmv_entries;
+
+ if (bmv->bmv_iflags & BMV_IF_NO_HOLES)
+ return;
+
+ p->bmv_block = -1;
+ p->bmv_offset = XFS_FSB_TO_BB(ip->i_mount, bno);
+ p->bmv_length = XFS_FSB_TO_BB(ip->i_mount, end - bno);
+
+ bmv->bmv_offset = p->bmv_offset + p->bmv_length;
+ bmv->bmv_length = max(0LL, bmv_end - bmv->bmv_offset);
+ bmv->bmv_entries++;
+}
+
+static inline bool
+xfs_getbmap_full(
+ struct getbmapx *bmv)
+{
+ return bmv->bmv_length == 0 || bmv->bmv_entries >= bmv->bmv_count - 1;
+}
+
+static bool
+xfs_getbmap_next_rec(
+ struct xfs_bmbt_irec *rec,
+ xfs_fileoff_t total_end)
+{
+ xfs_fileoff_t end = rec->br_startoff + rec->br_blockcount;
+
+ if (end == total_end)
+ return false;
+
+ rec->br_startoff += rec->br_blockcount;
+ if (!isnullstartblock(rec->br_startblock) &&
+ rec->br_startblock != DELAYSTARTBLOCK)
+ rec->br_startblock += rec->br_blockcount;
+ rec->br_blockcount = total_end - end;
+ return true;
+}
+
/*
* Get inode's extents as described in bmv, and format for output.
* Calls formatter to fill the user's buffer until all extents
@@ -540,119 +518,72 @@
xfs_bmap_format_t formatter, /* format to user */
void *arg) /* formatter arg */
{
- int64_t bmvend; /* last block requested */
- int error = 0; /* return value */
- int64_t fixlen; /* length for -1 case */
- int i; /* extent number */
- int lock; /* lock state */
- xfs_bmbt_irec_t *map; /* buffer for user's data */
- xfs_mount_t *mp; /* file system mount point */
- int nex; /* # of user extents can do */
- int subnex; /* # of bmapi's can do */
- int nmap; /* number of map entries */
- struct getbmapx *out; /* output structure */
- int whichfork; /* data or attr fork */
- int prealloced; /* this is a file with
- * preallocated data space */
- int iflags; /* interface flags */
- int bmapi_flags; /* flags for xfs_bmapi */
- int cur_ext = 0;
- struct xfs_bmbt_irec inject_map;
-
- mp = ip->i_mount;
- iflags = bmv->bmv_iflags;
+ struct xfs_mount *mp = ip->i_mount;
+ int iflags = bmv->bmv_iflags;
+ int whichfork, lock, i, error = 0;
+ int64_t bmv_end, max_len;
+ xfs_fileoff_t bno, first_bno;
+ struct xfs_ifork *ifp;
+ struct getbmapx *out;
+ struct xfs_bmbt_irec got, rec;
+ xfs_filblks_t len;
+ xfs_extnum_t idx;
#ifndef DEBUG
/* Only allow CoW fork queries if we're debugging. */
if (iflags & BMV_IF_COWFORK)
return -EINVAL;
#endif
+
if ((iflags & BMV_IF_ATTRFORK) && (iflags & BMV_IF_COWFORK))
return -EINVAL;
+ if (bmv->bmv_count <= 1)
+ return -EINVAL;
+ if (bmv->bmv_count > ULONG_MAX / sizeof(struct getbmapx))
+ return -ENOMEM;
+
+ if (bmv->bmv_length < -1)
+ return -EINVAL;
+
+ bmv->bmv_entries = 0;
+ if (bmv->bmv_length == 0)
+ return 0;
+
+ out = kmem_zalloc_large(bmv->bmv_count * sizeof(struct getbmapx), 0);
+ if (!out)
+ return -ENOMEM;
+
if (iflags & BMV_IF_ATTRFORK)
whichfork = XFS_ATTR_FORK;
else if (iflags & BMV_IF_COWFORK)
whichfork = XFS_COW_FORK;
else
whichfork = XFS_DATA_FORK;
-
- switch (whichfork) {
- case XFS_ATTR_FORK:
- if (XFS_IFORK_Q(ip)) {
- if (ip->i_d.di_aformat != XFS_DINODE_FMT_EXTENTS &&
- ip->i_d.di_aformat != XFS_DINODE_FMT_BTREE &&
- ip->i_d.di_aformat != XFS_DINODE_FMT_LOCAL)
- return -EINVAL;
- } else if (unlikely(
- ip->i_d.di_aformat != 0 &&
- ip->i_d.di_aformat != XFS_DINODE_FMT_EXTENTS)) {
- XFS_ERROR_REPORT("xfs_getbmap", XFS_ERRLEVEL_LOW,
- ip->i_mount);
- return -EFSCORRUPTED;
- }
-
- prealloced = 0;
- fixlen = 1LL << 32;
- break;
- case XFS_COW_FORK:
- if (ip->i_cformat != XFS_DINODE_FMT_EXTENTS)
- return -EINVAL;
-
- if (xfs_get_cowextsz_hint(ip)) {
- prealloced = 1;
- fixlen = mp->m_super->s_maxbytes;
- } else {
- prealloced = 0;
- fixlen = XFS_ISIZE(ip);
- }
- break;
- default:
- /* Local format data forks report no extents. */
- if (ip->i_d.di_format == XFS_DINODE_FMT_LOCAL) {
- bmv->bmv_entries = 0;
- return 0;
- }
- if (ip->i_d.di_format != XFS_DINODE_FMT_EXTENTS &&
- ip->i_d.di_format != XFS_DINODE_FMT_BTREE)
- return -EINVAL;
-
- if (xfs_get_extsz_hint(ip) ||
- ip->i_d.di_flags & (XFS_DIFLAG_PREALLOC|XFS_DIFLAG_APPEND)){
- prealloced = 1;
- fixlen = mp->m_super->s_maxbytes;
- } else {
- prealloced = 0;
- fixlen = XFS_ISIZE(ip);
- }
- break;
- }
-
- if (bmv->bmv_length == -1) {
- fixlen = XFS_FSB_TO_BB(mp, XFS_B_TO_FSB(mp, fixlen));
- bmv->bmv_length =
- max_t(int64_t, fixlen - bmv->bmv_offset, 0);
- } else if (bmv->bmv_length == 0) {
- bmv->bmv_entries = 0;
- return 0;
- } else if (bmv->bmv_length < 0) {
- return -EINVAL;
- }
-
- nex = bmv->bmv_count - 1;
- if (nex <= 0)
- return -EINVAL;
- bmvend = bmv->bmv_offset + bmv->bmv_length;
-
-
- if (bmv->bmv_count > ULONG_MAX / sizeof(struct getbmapx))
- return -ENOMEM;
- out = kmem_zalloc_large(bmv->bmv_count * sizeof(struct getbmapx), 0);
- if (!out)
- return -ENOMEM;
+ ifp = XFS_IFORK_PTR(ip, whichfork);
xfs_ilock(ip, XFS_IOLOCK_SHARED);
switch (whichfork) {
+ case XFS_ATTR_FORK:
+ if (!XFS_IFORK_Q(ip))
+ goto out_unlock_iolock;
+
+ max_len = 1LL << 32;
+ lock = xfs_ilock_attr_map_shared(ip);
+ break;
+ case XFS_COW_FORK:
+ /* No CoW fork? Just return */
+ if (!ifp)
+ goto out_unlock_iolock;
+
+ if (xfs_get_cowextsz_hint(ip))
+ max_len = mp->m_super->s_maxbytes;
+ else
+ max_len = XFS_ISIZE(ip);
+
+ lock = XFS_ILOCK_SHARED;
+ xfs_ilock(ip, lock);
+ break;
case XFS_DATA_FORK:
if (!(iflags & BMV_IF_DELALLOC) &&
(ip->i_delayed_blks || XFS_ISIZE(ip) > ip->i_d.di_size)) {
@@ -670,147 +601,107 @@
*/
}
+ if (xfs_get_extsz_hint(ip) ||
+ (ip->i_d.di_flags &
+ (XFS_DIFLAG_PREALLOC | XFS_DIFLAG_APPEND)))
+ max_len = mp->m_super->s_maxbytes;
+ else
+ max_len = XFS_ISIZE(ip);
+
lock = xfs_ilock_data_map_shared(ip);
break;
- case XFS_COW_FORK:
- lock = XFS_ILOCK_SHARED;
- xfs_ilock(ip, lock);
- break;
- case XFS_ATTR_FORK:
- lock = xfs_ilock_attr_map_shared(ip);
- break;
}
- /*
- * Don't let nex be bigger than the number of extents
- * we can have assuming alternating holes and real extents.
- */
- if (nex > XFS_IFORK_NEXTENTS(ip, whichfork) * 2 + 1)
- nex = XFS_IFORK_NEXTENTS(ip, whichfork) * 2 + 1;
-
- bmapi_flags = xfs_bmapi_aflag(whichfork);
- if (!(iflags & BMV_IF_PREALLOC))
- bmapi_flags |= XFS_BMAPI_IGSTATE;
-
- /*
- * Allocate enough space to handle "subnex" maps at a time.
- */
- error = -ENOMEM;
- subnex = 16;
- map = kmem_alloc(subnex * sizeof(*map), KM_MAYFAIL | KM_NOFS);
- if (!map)
+ switch (XFS_IFORK_FORMAT(ip, whichfork)) {
+ case XFS_DINODE_FMT_EXTENTS:
+ case XFS_DINODE_FMT_BTREE:
+ break;
+ case XFS_DINODE_FMT_LOCAL:
+ /* Local format inode forks report no extents. */
goto out_unlock_ilock;
-
- bmv->bmv_entries = 0;
-
- if (XFS_IFORK_NEXTENTS(ip, whichfork) == 0 &&
- (whichfork == XFS_ATTR_FORK || !(iflags & BMV_IF_DELALLOC))) {
- error = 0;
- goto out_free_map;
+ default:
+ error = -EINVAL;
+ goto out_unlock_ilock;
}
- do {
- nmap = (nex> subnex) ? subnex : nex;
- error = xfs_bmapi_read(ip, XFS_BB_TO_FSBT(mp, bmv->bmv_offset),
- XFS_BB_TO_FSB(mp, bmv->bmv_length),
- map, &nmap, bmapi_flags);
+ if (bmv->bmv_length == -1) {
+ max_len = XFS_FSB_TO_BB(mp, XFS_B_TO_FSB(mp, max_len));
+ bmv->bmv_length = max(0LL, max_len - bmv->bmv_offset);
+ }
+
+ bmv_end = bmv->bmv_offset + bmv->bmv_length;
+
+ first_bno = bno = XFS_BB_TO_FSBT(mp, bmv->bmv_offset);
+ len = XFS_BB_TO_FSB(mp, bmv->bmv_length);
+
+ if (!(ifp->if_flags & XFS_IFEXTENTS)) {
+ error = xfs_iread_extents(NULL, ip, whichfork);
if (error)
- goto out_free_map;
- ASSERT(nmap <= subnex);
+ goto out_unlock_ilock;
+ }
- for (i = 0; i < nmap && bmv->bmv_length &&
- cur_ext < bmv->bmv_count - 1; i++) {
- out[cur_ext].bmv_oflags = 0;
- if (map[i].br_state == XFS_EXT_UNWRITTEN)
- out[cur_ext].bmv_oflags |= BMV_OF_PREALLOC;
- else if (map[i].br_startblock == DELAYSTARTBLOCK)
- out[cur_ext].bmv_oflags |= BMV_OF_DELALLOC;
- out[cur_ext].bmv_offset =
- XFS_FSB_TO_BB(mp, map[i].br_startoff);
- out[cur_ext].bmv_length =
- XFS_FSB_TO_BB(mp, map[i].br_blockcount);
- out[cur_ext].bmv_unused1 = 0;
- out[cur_ext].bmv_unused2 = 0;
+ if (!xfs_iext_lookup_extent(ip, ifp, bno, &idx, &got)) {
+ /*
+ * Report a whole-file hole if the delalloc flag is set to
+ * stay compatible with the old implementation.
+ */
+ if (iflags & BMV_IF_DELALLOC)
+ xfs_getbmap_report_hole(ip, bmv, out, bmv_end, bno,
+ XFS_B_TO_FSB(mp, XFS_ISIZE(ip)));
+ goto out_unlock_ilock;
+ }
- /*
- * delayed allocation extents that start beyond EOF can
- * occur due to speculative EOF allocation when the
- * delalloc extent is larger than the largest freespace
- * extent at conversion time. These extents cannot be
- * converted by data writeback, so can exist here even
- * if we are not supposed to be finding delalloc
- * extents.
- */
- if (map[i].br_startblock == DELAYSTARTBLOCK &&
- map[i].br_startoff < XFS_B_TO_FSB(mp, XFS_ISIZE(ip)))
- ASSERT((iflags & BMV_IF_DELALLOC) != 0);
+ while (!xfs_getbmap_full(bmv)) {
+ xfs_trim_extent(&got, first_bno, len);
- if (map[i].br_startblock == HOLESTARTBLOCK &&
- whichfork == XFS_ATTR_FORK) {
- /* came to the end of attribute fork */
- out[cur_ext].bmv_oflags |= BMV_OF_LAST;
- goto out_free_map;
- }
-
- /* Is this a shared block? */
- error = xfs_getbmap_adjust_shared(ip, whichfork,
- &map[i], &out[cur_ext], &inject_map);
- if (error)
- goto out_free_map;
-
- if (!xfs_getbmapx_fix_eof_hole(ip, whichfork,
- &out[cur_ext], prealloced, bmvend,
- map[i].br_startblock,
- inject_map.br_startblock != NULLFSBLOCK))
- goto out_free_map;
-
- bmv->bmv_offset =
- out[cur_ext].bmv_offset +
- out[cur_ext].bmv_length;
- bmv->bmv_length =
- max_t(int64_t, 0, bmvend - bmv->bmv_offset);
-
- /*
- * In case we don't want to return the hole,
- * don't increase cur_ext so that we can reuse
- * it in the next loop.
- */
- if ((iflags & BMV_IF_NO_HOLES) &&
- map[i].br_startblock == HOLESTARTBLOCK) {
- memset(&out[cur_ext], 0, sizeof(out[cur_ext]));
- continue;
- }
-
- /*
- * In order to report shared extents accurately,
- * we report each distinct shared/unshared part
- * of a single bmbt record using multiple bmap
- * extents. To make that happen, we iterate the
- * same map array item multiple times, each
- * time trimming out the subextent that we just
- * reported.
- *
- * Because of this, we must check the out array
- * index (cur_ext) directly against bmv_count-1
- * to avoid overflows.
- */
- if (inject_map.br_startblock != NULLFSBLOCK) {
- map[i] = inject_map;
- i--;
- }
- bmv->bmv_entries++;
- cur_ext++;
+ /*
+ * Report an entry for a hole if this extent doesn't directly
+ * follow the previous one.
+ */
+ if (got.br_startoff > bno) {
+ xfs_getbmap_report_hole(ip, bmv, out, bmv_end, bno,
+ got.br_startoff);
+ if (xfs_getbmap_full(bmv))
+ break;
}
- } while (nmap && bmv->bmv_length && cur_ext < bmv->bmv_count - 1);
- out_free_map:
- kmem_free(map);
- out_unlock_ilock:
+ /*
+ * In order to report shared extents accurately, we report each
+ * distinct shared / unshared part of a single bmbt record with
+ * an individual getbmapx record.
+ */
+ bno = got.br_startoff + got.br_blockcount;
+ rec = got;
+ do {
+ error = xfs_getbmap_report_one(ip, bmv, out, bmv_end,
+ &rec);
+ if (error || xfs_getbmap_full(bmv))
+ goto out_unlock_ilock;
+ } while (xfs_getbmap_next_rec(&rec, bno));
+
+ if (!xfs_iext_get_extent(ifp, ++idx, &got)) {
+ xfs_fileoff_t end = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
+
+ out[bmv->bmv_entries - 1].bmv_oflags |= BMV_OF_LAST;
+
+ if (whichfork != XFS_ATTR_FORK && bno < end &&
+ !xfs_getbmap_full(bmv)) {
+ xfs_getbmap_report_hole(ip, bmv, out, bmv_end,
+ bno, end);
+ }
+ break;
+ }
+
+ if (bno >= first_bno + len)
+ break;
+ }
+
+out_unlock_ilock:
xfs_iunlock(ip, lock);
- out_unlock_iolock:
+out_unlock_iolock:
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
- for (i = 0; i < cur_ext; i++) {
+ for (i = 0; i < bmv->bmv_entries; i++) {
/* format results & advance arg */
error = formatter(&arg, &out[i]);
if (error)