xfs: introduce xfs_bmapi_read()

xfs_bmapi() currently handles both extent map reading and
allocation. As a result, the code is littered with "if (wr)"
branches to conditionally do allocation operations if required.
This makes the code much harder to follow and causes significant
indent issues with the code.

Given that read mapping is much simpler than allocation, we can
split out read mapping from xfs_bmapi() and reuse the logic that
we have already factored out do do all the hard work of handling the
extent map manipulations. The results in a much simpler function for
the common extent read operations, and will allow the allocation
code to be simplified in another commit.

Once xfs_bmapi_read() is implemented, convert all the callers of
xfs_bmapi() that are only reading extents to use the new function.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

13 files changed, 151 insertions, 77 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 22aadf667862..11b2aad982d4 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -315,8 +315,8 @@ xfs_map_blocks(
                 count = mp->m_maxioffset - offset;
         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
         offset_fsb = XFS_B_TO_FSBT(mp, offset);
-        error = xfs_bmapi(NULL, ip, offset_fsb, end_fsb - offset_fsb,
-                          bmapi_flags,  NULL, 0, imap, &nimaps, NULL);
+        error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
+                                imap, &nimaps, bmapi_flags);
         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 
         if (error)
@@ -1138,8 +1138,8 @@ __xfs_get_blocks(
         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + size);
         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 
-        error = xfs_bmapi(NULL, ip, offset_fsb, end_fsb - offset_fsb,
-                          XFS_BMAPI_ENTIRE,  NULL, 0, &imap, &nimaps, NULL);
+        error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
+                                &imap, &nimaps, XFS_BMAPI_ENTIRE);
         if (error)
                 goto out_unlock;
 
diff --git a/fs/xfs/xfs_attr.c b/fs/xfs/xfs_attr.c
index c7dab0c0bdda..41ef02b7185a 100644
--- a/fs/xfs/xfs_attr.c
+++ b/fs/xfs/xfs_attr.c
@@ -1963,10 +1963,9 @@ xfs_attr_rmtval_get(xfs_da_args_t *args)
         lblkno = args->rmtblkno;
         while (valuelen > 0) {
                 nmap = ATTR_RMTVALUE_MAPSIZE;
-                error = xfs_bmapi(args->trans, args->dp, (xfs_fileoff_t)lblkno,
-                                  args->rmtblkcnt,
-                                  XFS_BMAPI_ATTRFORK | XFS_BMAPI_METADATA,
-                                  NULL, 0, map, &nmap, NULL);
+                error = xfs_bmapi_read(args->dp, (xfs_fileoff_t)lblkno,
+                                       args->rmtblkcnt, map, &nmap,
+                                       XFS_BMAPI_ATTRFORK);
                 if (error)
                         return(error);
                 ASSERT(nmap >= 1);
@@ -2092,14 +2091,11 @@ xfs_attr_rmtval_set(xfs_da_args_t *args)
                  */
                 xfs_bmap_init(args->flist, args->firstblock);
                 nmap = 1;
-                error = xfs_bmapi(NULL, dp, (xfs_fileoff_t)lblkno,
-                                  args->rmtblkcnt,
-                                  XFS_BMAPI_ATTRFORK | XFS_BMAPI_METADATA,
-                                  args->firstblock, 0, &map, &nmap,
-                                  NULL);
-                if (error) {
+                error = xfs_bmapi_read(dp, (xfs_fileoff_t)lblkno,
+                                       args->rmtblkcnt, &map, &nmap,
+                                       XFS_BMAPI_ATTRFORK);
+                if (error)
                         return(error);
-                }
                 ASSERT(nmap == 1);
                 ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
                        (map.br_startblock != HOLESTARTBLOCK));
@@ -2155,16 +2151,12 @@ xfs_attr_rmtval_remove(xfs_da_args_t *args)
                 /*
                  * Try to remember where we decided to put the value.
                  */
-                xfs_bmap_init(args->flist, args->firstblock);
                 nmap = 1;
-                error = xfs_bmapi(NULL, args->dp, (xfs_fileoff_t)lblkno,
-                                        args->rmtblkcnt,
-                                        XFS_BMAPI_ATTRFORK | XFS_BMAPI_METADATA,
-                                        args->firstblock, 0, &map, &nmap,
-                                        args->flist);
-                if (error) {
+                error = xfs_bmapi_read(args->dp, (xfs_fileoff_t)lblkno,
+                                       args->rmtblkcnt, &map, &nmap,
+                                       XFS_BMAPI_ATTRFORK);
+                if (error)
                         return(error);
-                }
                 ASSERT(nmap == 1);
                 ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
                        (map.br_startblock != HOLESTARTBLOCK));
diff --git a/fs/xfs/xfs_attr_leaf.c b/fs/xfs/xfs_attr_leaf.c
index 58c3add07b65..d4906e7c9787 100644
--- a/fs/xfs/xfs_attr_leaf.c
+++ b/fs/xfs/xfs_attr_leaf.c
@@ -2926,9 +2926,8 @@ xfs_attr_leaf_freextent(xfs_trans_t **trans, xfs_inode_t *dp,
                  * Try to remember where we decided to put the value.
                  */
                 nmap = 1;
-                error = xfs_bmapi(*trans, dp, (xfs_fileoff_t)tblkno, tblkcnt,
-                                        XFS_BMAPI_ATTRFORK | XFS_BMAPI_METADATA,
-                                        NULL, 0, &map, &nmap, NULL);
+                error = xfs_bmapi_read(dp, (xfs_fileoff_t)tblkno, tblkcnt,
+                                       &map, &nmap, XFS_BMAPI_ATTRFORK);
                 if (error) {
                         return(error);
                 }
diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 59f63949d3bc..fc5acf0b921e 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -4350,6 +4350,98 @@ xfs_bmapi_update_map(
 }
 
 /*
+ * Map file blocks to filesystem blocks without allocation.
+ */
+int
+xfs_bmapi_read(
+        struct xfs_inode        *ip,
+        xfs_fileoff_t           bno,
+        xfs_filblks_t           len,
+        struct xfs_bmbt_irec    *mval,
+        int                     *nmap,
+        int                     flags)
+{
+        struct xfs_mount        *mp = ip->i_mount;
+        struct xfs_ifork        *ifp;
+        struct xfs_bmbt_irec    got;
+        struct xfs_bmbt_irec    prev;
+        xfs_fileoff_t           obno;
+        xfs_fileoff_t           end;
+        xfs_extnum_t            lastx;
+        int                     error;
+        int                     eof;
+        int                     n = 0;
+        int                     whichfork = (flags & XFS_BMAPI_ATTRFORK) ?
+                                                XFS_ATTR_FORK : XFS_DATA_FORK;
+
+        ASSERT(*nmap >= 1);
+        ASSERT(!(flags & ~(XFS_BMAPI_ATTRFORK|XFS_BMAPI_ENTIRE|
+                           XFS_BMAPI_IGSTATE)));
+
+        if (unlikely(XFS_TEST_ERROR(
+            (XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
+             XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_BTREE),
+             mp, XFS_ERRTAG_BMAPIFORMAT, XFS_RANDOM_BMAPIFORMAT))) {
+                XFS_ERROR_REPORT("xfs_bmapi_read", XFS_ERRLEVEL_LOW, mp);
+                return XFS_ERROR(EFSCORRUPTED);
+        }
+
+        if (XFS_FORCED_SHUTDOWN(mp))
+                return XFS_ERROR(EIO);
+
+        XFS_STATS_INC(xs_blk_mapr);
+
+        ifp = XFS_IFORK_PTR(ip, whichfork);
+        ASSERT(ifp->if_ext_max ==
+               XFS_IFORK_SIZE(ip, whichfork) / (uint)sizeof(xfs_bmbt_rec_t));
+
+        if (!(ifp->if_flags & XFS_IFEXTENTS)) {
+                error = xfs_iread_extents(NULL, ip, whichfork);
+                if (error)
+                        return error;
+        }
+
+        xfs_bmap_search_extents(ip, bno, whichfork, &eof, &lastx, &got, &prev);
+        end = bno + len;
+        obno = bno;
+
+        while (bno < end && n < *nmap) {
+                /* Reading past eof, act as though there's a hole up to end. */
+                if (eof)
+                        got.br_startoff = end;
+                if (got.br_startoff > bno) {
+                        /* Reading in a hole.  */
+                        mval->br_startoff = bno;
+                        mval->br_startblock = HOLESTARTBLOCK;
+                        mval->br_blockcount =
+                                XFS_FILBLKS_MIN(len, got.br_startoff - bno);
+                        mval->br_state = XFS_EXT_NORM;
+                        bno += mval->br_blockcount;
+                        len -= mval->br_blockcount;
+                        mval++;
+                        n++;
+                        continue;
+                }
+
+                /* set up the extent map to return. */
+                xfs_bmapi_trim_map(mval, &got, &bno, len, obno, end, n, flags);
+                xfs_bmapi_update_map(&mval, &bno, &len, obno, end, &n, flags);
+
+                /* If we're done, stop now. */
+                if (bno >= end || n >= *nmap)
+                        break;
+
+                /* Else go on to the next record. */
+                if (++lastx < ifp->if_bytes / sizeof(xfs_bmbt_rec_t))
+                        xfs_bmbt_get_all(xfs_iext_get_ext(ifp, lastx), &got);
+                else
+                        eof = 1;
+        }
+        *nmap = n;
+        return 0;
+}
+
+/*
  * Map file blocks to filesystem blocks.
  * File range is given by the bno/len pair.
  * Adds blocks to file if a write ("flags & XFS_BMAPI_WRITE" set)
@@ -5490,10 +5582,9 @@ xfs_getbmap(
 
         do {
                 nmap = (nexleft > subnex) ? subnex : nexleft;
-                error = xfs_bmapi(NULL, ip, XFS_BB_TO_FSBT(mp, bmv->bmv_offset),
-                                  XFS_BB_TO_FSB(mp, bmv->bmv_length),
-                                  bmapi_flags, NULL, 0, map, &nmap,
-                                  NULL);
+                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);
@@ -6084,9 +6175,8 @@ xfs_bmap_punch_delalloc_range(
                  * trying to remove a real extent (which requires a
                  * transaction) or a hole, which is probably a bad idea...
                  */
-                error = xfs_bmapi(NULL, ip, start_fsb, 1,
-                                XFS_BMAPI_ENTIRE,  NULL, 0, &imap,
-                                &nimaps, NULL);
+                error = xfs_bmapi_read(ip, start_fsb, 1, &imap, &nimaps,
+                                       XFS_BMAPI_ENTIRE);
 
                 if (error) {
                         /* something screwed, just bail */
diff --git a/fs/xfs/xfs_bmap.h b/fs/xfs/xfs_bmap.h
index c62234bde053..16257c6eba71 100644
--- a/fs/xfs/xfs_bmap.h
+++ b/fs/xfs/xfs_bmap.h
@@ -294,6 +294,10 @@ xfs_bmapi(
         int                     *nmap,          /* i/o: mval size/count */
         xfs_bmap_free_t         *flist);        /* i/o: list extents to free */
 
+int     xfs_bmapi_read(struct xfs_inode *ip, xfs_fileoff_t bno,
+                xfs_filblks_t len, struct xfs_bmbt_irec *mval,
+                int *nmap, int flags);
+
 /*
  * Map file blocks to filesystem blocks, simple version.
  * One block only, read-only.
diff --git a/fs/xfs/xfs_da_btree.c b/fs/xfs/xfs_da_btree.c
index ee9d5427fcd4..44dfa39099ef 100644
--- a/fs/xfs/xfs_da_btree.c
+++ b/fs/xfs/xfs_da_btree.c
@@ -1995,11 +1995,10 @@ xfs_da_do_buf(
                 } else {
                         mapp = kmem_alloc(sizeof(*mapp) * nfsb, KM_SLEEP);
                         nmap = nfsb;
-                        if ((error = xfs_bmapi(trans, dp, (xfs_fileoff_t)bno,
-                                        nfsb,
-                                        XFS_BMAPI_METADATA |
-                                                xfs_bmapi_aflag(whichfork),
-                                        NULL, 0, mapp, &nmap, NULL)))
+                        error = xfs_bmapi_read(dp, (xfs_fileoff_t)bno, nfsb,
+                                               mapp, &nmap,
+                                               xfs_bmapi_aflag(whichfork));
+                        if (error)
                                 goto exit0;
                 }
         } else {
diff --git a/fs/xfs/xfs_dir2_leaf.c b/fs/xfs/xfs_dir2_leaf.c
index ca2386d82cdf..66e108f561a3 100644
--- a/fs/xfs/xfs_dir2_leaf.c
+++ b/fs/xfs/xfs_dir2_leaf.c
@@ -888,12 +888,10 @@ xfs_dir2_leaf_getdents(
                                  * we already have in the table.
                                  */
                                 nmap = map_size - map_valid;
-                                error = xfs_bmapi(NULL, dp,
-                                        map_off,
+                                error = xfs_bmapi_read(dp, map_off,
                                         xfs_dir2_byte_to_da(mp,
                                                 XFS_DIR2_LEAF_OFFSET) - map_off,
-                                        XFS_BMAPI_METADATA, NULL, 0,
-                                        &map[map_valid], &nmap, NULL);
+                                        &map[map_valid], &nmap, 0);
                                 /*
                                  * Don't know if we should ignore this or
                                  * try to return an error.
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 0c5fe66ce92b..c377961657ee 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -488,9 +488,8 @@ xfs_qm_dqtobp(
         /*
          * Find the block map; no allocations yet
          */
-        error = xfs_bmapi(NULL, quotip, dqp->q_fileoffset,
-                          XFS_DQUOT_CLUSTER_SIZE_FSB, XFS_BMAPI_METADATA,
-                          NULL, 0, &map, &nmaps, NULL);
+        error = xfs_bmapi_read(quotip, dqp->q_fileoffset,
+                               XFS_DQUOT_CLUSTER_SIZE_FSB, &map, &nmaps, 0);
 
         xfs_iunlock(quotip, XFS_ILOCK_SHARED);
         if (error)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 06fe97e56e48..558543c146b3 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -509,11 +509,9 @@ xfs_zero_last_block(
 
         last_fsb = XFS_B_TO_FSBT(mp, isize);
         nimaps = 1;
-        error = xfs_bmapi(NULL, ip, last_fsb, 1, 0, NULL, 0, &imap,
-                          &nimaps, NULL);
-        if (error) {
+        error = xfs_bmapi_read(ip, last_fsb, 1, &imap, &nimaps, 0);
+        if (error)
                 return error;
-        }
         ASSERT(nimaps > 0);
         /*
          * If the block underlying isize is just a hole, then there
@@ -604,8 +602,8 @@ xfs_zero_eof(
         while (start_zero_fsb <= end_zero_fsb) {
                 nimaps = 1;
                 zero_count_fsb = end_zero_fsb - start_zero_fsb + 1;
-                error = xfs_bmapi(NULL, ip, start_zero_fsb, zero_count_fsb,
-                                  0, NULL, 0, &imap, &nimaps, NULL);
+                error = xfs_bmapi_read(ip, start_zero_fsb, zero_count_fsb,
+                                          &imap, &nimaps, 0);
                 if (error) {
                         ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_IOLOCK_EXCL));
                         return error;
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index d689253fdfda..f690d3a10b34 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1187,6 +1187,7 @@ xfs_isize_check(
         xfs_fileoff_t           map_first;
         int                     nimaps;
         xfs_bmbt_irec_t         imaps[2];
+        int                     error;
 
         if (!S_ISREG(ip->i_d.di_mode))
                 return;
@@ -1203,13 +1204,12 @@ xfs_isize_check(
          * The filesystem could be shutting down, so bmapi may return
          * an error.
          */
-        if (xfs_bmapi(NULL, ip, map_first,
+        error = xfs_bmapi_read(ip, map_first,
                          (XFS_B_TO_FSB(mp,
-                                       (xfs_ufsize_t)XFS_MAXIOFFSET(mp)) -
-                          map_first),
-                         XFS_BMAPI_ENTIRE, NULL, 0, imaps, &nimaps,
-                         NULL))
-            return;
+                               (xfs_ufsize_t)XFS_MAXIOFFSET(mp)) - map_first),
+                         imaps, &nimaps, XFS_BMAPI_ENTIRE);
+        if (error)
+                return;
         ASSERT(nimaps == 1);
         ASSERT(imaps[0].br_startblock == HOLESTARTBLOCK);
 }
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 091d82b94c4d..544f053860f1 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -300,8 +300,8 @@ xfs_iomap_eof_want_preallocate(
         while (count_fsb > 0) {
                 imaps = nimaps;
                 firstblock = NULLFSBLOCK;
-                error = xfs_bmapi(NULL, ip, start_fsb, count_fsb, 0,
-                                  &firstblock, 0, imap, &imaps, NULL);
+                error = xfs_bmapi_read(ip, start_fsb, count_fsb, imap, &imaps,
+                                       0);
                 if (error)
                         return error;
                 for (n = 0; n < imaps; n++) {
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index f51bef885e6d..ddaf97a57ec6 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -1347,11 +1347,8 @@ xfs_qm_dqiterate(
                  * the inode is never added to the transaction.
                  */
                 xfs_ilock(qip, XFS_ILOCK_SHARED);
-                error = xfs_bmapi(NULL, qip, lblkno,
-                                  maxlblkcnt - lblkno,
-                                  XFS_BMAPI_METADATA,
-                                  NULL,
-                                  0, map, &nmaps, NULL);
+                error = xfs_bmapi_read(qip, lblkno, maxlblkcnt - lblkno,
+                                       map, &nmaps, 0);
                 xfs_iunlock(qip, XFS_ILOCK_SHARED);
                 if (error)
                         break;
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 0d1caec873a1..63874a87b378 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -72,8 +72,8 @@ xfs_readlink_bmap(
         xfs_buf_t       *bp;
         int             error = 0;
 
-        error = xfs_bmapi(NULL, ip, 0, XFS_B_TO_FSB(mp, pathlen), 0, NULL, 0,
-                        mval, &nmaps, NULL);
+        error = xfs_bmapi_read(ip, 0, XFS_B_TO_FSB(mp, pathlen), mval, &nmaps,
+                               0);
         if (error)
                 goto out;
 
@@ -178,8 +178,7 @@ xfs_free_eofblocks(
 
         nimaps = 1;
         xfs_ilock(ip, XFS_ILOCK_SHARED);
-        error = xfs_bmapi(NULL, ip, end_fsb, map_len, 0,
-                          NULL, 0, &imap, &nimaps, NULL);
+        error = xfs_bmapi_read(ip, end_fsb, map_len, &imap, &nimaps, 0);
         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 
         if (!error && (nimaps != 0) &&
@@ -297,9 +296,9 @@ xfs_inactive_symlink_rmt(
         done = 0;
         xfs_bmap_init(&free_list, &first_block);
         nmaps = ARRAY_SIZE(mval);
-        if ((error = xfs_bmapi(tp, ip, 0, XFS_B_TO_FSB(mp, size),
-                        XFS_BMAPI_METADATA, &first_block, 0, mval, &nmaps,
-                        &free_list)))
+        error = xfs_bmapi_read(ip, 0, XFS_B_TO_FSB(mp, size),
+                                mval, &nmaps, 0);
+        if (error)
                 goto error0;
         /*
          * Invalidate the block(s).
@@ -1981,8 +1980,7 @@ xfs_zero_remaining_bytes(
         for (offset = startoff; offset <= endoff; offset = lastoffset + 1) {
                 offset_fsb = XFS_B_TO_FSBT(mp, offset);
                 nimap = 1;
-                error = xfs_bmapi(NULL, ip, offset_fsb, 1, 0,
-                        NULL, 0, &imap, &nimap, NULL);
+                error = xfs_bmapi_read(ip, offset_fsb, 1, &imap, &nimap, 0);
                 if (error || nimap < 1)
                         break;
                 ASSERT(imap.br_blockcount >= 1);
@@ -2101,8 +2099,8 @@ xfs_free_file_space(
          */
         if (rt && !xfs_sb_version_hasextflgbit(&mp->m_sb)) {
                 nimap = 1;
-                error = xfs_bmapi(NULL, ip, startoffset_fsb,
-                        1, 0, NULL, 0, &imap, &nimap, NULL);
+                error = xfs_bmapi_read(ip, startoffset_fsb, 1,
+                                        &imap, &nimap, 0);
                 if (error)
                         goto out_unlock_iolock;
                 ASSERT(nimap == 0 || nimap == 1);
@@ -2116,8 +2114,8 @@ xfs_free_file_space(
                                 startoffset_fsb += mp->m_sb.sb_rextsize - mod;
                 }
                 nimap = 1;
-                error = xfs_bmapi(NULL, ip, endoffset_fsb - 1,
-                        1, 0, NULL, 0, &imap, &nimap, NULL);
+                error = xfs_bmapi_read(ip, endoffset_fsb - 1, 1,
+                                        &imap, &nimap, 0);
                 if (error)
                         goto out_unlock_iolock;
                 ASSERT(nimap == 0 || nimap == 1);