From abbf9e8a45074844efc91990a75dfe47fab70fa6 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 17 Oct 2017 14:16:18 -0700 Subject: [PATCH] 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 Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_bmap_util.c | 525 ++++++++++++++++++++----------------------------- 1 file changed, 208 insertions(+), 317 deletions(-) diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c index 6503cfa..2564b8b3 100644 --- a/fs/xfs/xfs_bmap_util.c +++ b/fs/xfs/xfs_bmap_util.c @@ -405,125 +405,103 @@ xfs_bmap_count_blocks( 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; - - 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; - } + struct getbmapx *p = out + bmv->bmv_entries; + bool shared = false, trimmed = false; + int error; + + error = xfs_reflink_trim_around_shared(ip, got, &shared, &trimmed); + if (error) + return error; + + if (isnullstartblock(got->br_startblock) || + got->br_startblock == DELAYSTARTBLOCK) { + /* + * 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. + */ + 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 { - 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; + p->bmv_block = xfs_fsb_to_db(ip, got->br_startblock); } - return 1; + 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; } -/* 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) +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 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; + struct getbmapx *p = out + bmv->bmv_entries; - next_map->br_startblock = NULLFSBLOCK; - next_map->br_startoff = NULLFILEOFF; - next_map->br_blockcount = 0; + if (bmv->bmv_iflags & BMV_IF_NO_HOLES) + return; - /* 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; + 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); - 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); - if (error) - return error; + bmv->bmv_offset = p->bmv_offset + p->bmv_length; + bmv->bmv_length = max(0LL, bmv_end - bmv->bmv_offset); + bmv->bmv_entries++; +} - if (ebno == NULLAGBLOCK) { - /* No shared blocks at all. */ - return 0; - } else if (agbno == ebno) { - /* - * 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. - */ - 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; - } 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; - } +static inline bool +xfs_getbmap_full( + struct getbmapx *bmv) +{ + return bmv->bmv_length == 0 || bmv->bmv_entries >= bmv->bmv_count - 1; +} - return 0; +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; } /* @@ -540,119 +518,72 @@ xfs_getbmap( 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; + ifp = XFS_IFORK_PTR(ip, whichfork); + xfs_ilock(ip, XFS_IOLOCK_SHARED); 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; - } + if (!XFS_IFORK_Q(ip)) + goto out_unlock_iolock; - prealloced = 0; - fixlen = 1LL << 32; + max_len = 1LL << 32; + lock = xfs_ilock_attr_map_shared(ip); break; case XFS_COW_FORK: - if (ip->i_cformat != XFS_DINODE_FMT_EXTENTS) - return -EINVAL; + /* No CoW fork? Just return */ + if (!ifp) + goto out_unlock_iolock; - 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_cowextsz_hint(ip)) + max_len = mp->m_super->s_maxbytes; + else + max_len = XFS_ISIZE(ip); - 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); - } + lock = XFS_ILOCK_SHARED; + xfs_ilock(ip, lock); 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; - - xfs_ilock(ip, XFS_IOLOCK_SHARED); - switch (whichfork) { 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 @@ xfs_getbmap( */ } + 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; + default: + error = -EINVAL; + 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; + 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); } - 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 (error) - goto out_free_map; - ASSERT(nmap <= subnex); - - 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; + bmv_end = bmv->bmv_offset + bmv->bmv_length; - /* - * 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); - - 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; - } + first_bno = bno = XFS_BB_TO_FSBT(mp, bmv->bmv_offset); + len = XFS_BB_TO_FSB(mp, bmv->bmv_length); - /* 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 (!(ifp->if_flags & XFS_IFEXTENTS)) { + error = xfs_iread_extents(NULL, ip, whichfork); + if (error) + goto out_unlock_ilock; + } - 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; + 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; + } - 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); + while (!xfs_getbmap_full(bmv)) { + xfs_trim_extent(&got, first_bno, len); - /* - * 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; - } + /* + * 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; + } - /* - * 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--; + /* + * 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); } - bmv->bmv_entries++; - cur_ext++; + break; } - } while (nmap && bmv->bmv_length && cur_ext < bmv->bmv_count - 1); - out_free_map: - kmem_free(map); - out_unlock_ilock: + 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) -- 2.7.4