+struct xfs_dir2_leaf_map_info {
+ xfs_extlen_t map_blocks; /* number of fsbs in map */
+ xfs_dablk_t map_off; /* last mapped file offset */
+ int map_size; /* total entries in *map */
+ int map_valid; /* valid entries in *map */
+ int nmap; /* mappings to ask xfs_bmapi */
+ xfs_dir2_db_t curdb; /* db for current block */
+ int ra_current; /* number of read-ahead blks */
+ int ra_index; /* *map index for read-ahead */
+ int ra_offset; /* map entry offset for ra */
+ int ra_want; /* readahead count wanted */
+ struct xfs_bmbt_irec map[]; /* map vector for blocks */
+};
+
+STATIC int
+xfs_dir2_leaf_readbuf(
+ struct xfs_inode *dp,
+ size_t bufsize,
+ struct xfs_dir2_leaf_map_info *mip,
+ xfs_dir2_off_t *curoff,
+ struct xfs_buf **bpp)
+{
+ struct xfs_mount *mp = dp->i_mount;
+ struct xfs_buf *bp = *bpp;
+ struct xfs_bmbt_irec *map = mip->map;
+ int error = 0;
+ int length;
+ int i;
+ int j;
+
+ /*
+ * If we have a buffer, we need to release it and
+ * take it out of the mapping.
+ */
+
+ if (bp) {
+ xfs_trans_brelse(NULL, bp);
+ bp = NULL;
+ mip->map_blocks -= mp->m_dirblkfsbs;
+ /*
+ * Loop to get rid of the extents for the
+ * directory block.
+ */
+ for (i = mp->m_dirblkfsbs; i > 0; ) {
+ j = min_t(int, map->br_blockcount, i);
+ map->br_blockcount -= j;
+ map->br_startblock += j;
+ map->br_startoff += j;
+ /*
+ * If mapping is done, pitch it from
+ * the table.
+ */
+ if (!map->br_blockcount && --mip->map_valid)
+ memmove(&map[0], &map[1],
+ sizeof(map[0]) * mip->map_valid);
+ i -= j;
+ }
+ }
+
+ /*
+ * Recalculate the readahead blocks wanted.
+ */
+ mip->ra_want = howmany(bufsize + mp->m_dirblksize,
+ mp->m_sb.sb_blocksize) - 1;
+ ASSERT(mip->ra_want >= 0);
+
+ /*
+ * If we don't have as many as we want, and we haven't
+ * run out of data blocks, get some more mappings.
+ */
+ if (1 + mip->ra_want > mip->map_blocks &&
+ mip->map_off < xfs_dir2_byte_to_da(mp, XFS_DIR2_LEAF_OFFSET)) {
+ /*
+ * Get more bmaps, fill in after the ones
+ * we already have in the table.
+ */
+ mip->nmap = mip->map_size - mip->map_valid;
+ error = xfs_bmapi_read(dp, mip->map_off,
+ xfs_dir2_byte_to_da(mp, XFS_DIR2_LEAF_OFFSET) -
+ mip->map_off,
+ &map[mip->map_valid], &mip->nmap, 0);
+
+ /*
+ * Don't know if we should ignore this or try to return an
+ * error. The trouble with returning errors is that readdir
+ * will just stop without actually passing the error through.
+ */
+ if (error)
+ goto out; /* XXX */
+
+ /*
+ * If we got all the mappings we asked for, set the final map
+ * offset based on the last bmap value received. Otherwise,
+ * we've reached the end.
+ */
+ if (mip->nmap == mip->map_size - mip->map_valid) {
+ i = mip->map_valid + mip->nmap - 1;
+ mip->map_off = map[i].br_startoff + map[i].br_blockcount;
+ } else
+ mip->map_off = xfs_dir2_byte_to_da(mp,
+ XFS_DIR2_LEAF_OFFSET);
+
+ /*
+ * Look for holes in the mapping, and eliminate them. Count up
+ * the valid blocks.
+ */
+ for (i = mip->map_valid; i < mip->map_valid + mip->nmap; ) {
+ if (map[i].br_startblock == HOLESTARTBLOCK) {
+ mip->nmap--;
+ length = mip->map_valid + mip->nmap - i;
+ if (length)
+ memmove(&map[i], &map[i + 1],
+ sizeof(map[i]) * length);
+ } else {
+ mip->map_blocks += map[i].br_blockcount;
+ i++;
+ }
+ }
+ mip->map_valid += mip->nmap;
+ }
+
+ /*
+ * No valid mappings, so no more data blocks.
+ */
+ if (!mip->map_valid) {
+ *curoff = xfs_dir2_da_to_byte(mp, mip->map_off);
+ goto out;
+ }
+
+ /*
+ * Read the directory block starting at the first mapping.
+ */
+ mip->curdb = xfs_dir2_da_to_db(mp, map->br_startoff);
+ error = xfs_da_read_buf(NULL, dp, map->br_startoff,
+ map->br_blockcount >= mp->m_dirblkfsbs ?
+ XFS_FSB_TO_DADDR(mp, map->br_startblock) : -1,
+ &bp, XFS_DATA_FORK);
+
+ /*
+ * Should just skip over the data block instead of giving up.
+ */
+ if (error)
+ goto out; /* XXX */
+
+ /*
+ * Adjust the current amount of read-ahead: we just read a block that
+ * was previously ra.
+ */
+ if (mip->ra_current)
+ mip->ra_current -= mp->m_dirblkfsbs;
+
+ /*
+ * Do we need more readahead?
+ */
+ for (mip->ra_index = mip->ra_offset = i = 0;
+ mip->ra_want > mip->ra_current && i < mip->map_blocks;
+ i += mp->m_dirblkfsbs) {
+ ASSERT(mip->ra_index < mip->map_valid);
+ /*
+ * Read-ahead a contiguous directory block.
+ */
+ if (i > mip->ra_current &&
+ map[mip->ra_index].br_blockcount >= mp->m_dirblkfsbs) {
+ xfs_buf_readahead(mp->m_ddev_targp,
+ XFS_FSB_TO_DADDR(mp,
+ map[mip->ra_index].br_startblock +
+ mip->ra_offset),
+ (int)BTOBB(mp->m_dirblksize));
+ mip->ra_current = i;
+ }
+
+ /*
+ * Read-ahead a non-contiguous directory block. This doesn't
+ * use our mapping, but this is a very rare case.
+ */
+ else if (i > mip->ra_current) {
+ xfs_da_reada_buf(NULL, dp,
+ map[mip->ra_index].br_startoff +
+ mip->ra_offset,
+ XFS_DATA_FORK);
+ mip->ra_current = i;
+ }
+
+ /*
+ * Advance offset through the mapping table.
+ */
+ for (j = 0; j < mp->m_dirblkfsbs; j++) {
+ /*
+ * The rest of this extent but not more than a dir
+ * block.
+ */
+ length = min_t(int, mp->m_dirblkfsbs,
+ map[mip->ra_index].br_blockcount -
+ mip->ra_offset);
+ j += length;
+ mip->ra_offset += length;
+
+ /*
+ * Advance to the next mapping if this one is used up.
+ */
+ if (mip->ra_offset == map[mip->ra_index].br_blockcount) {
+ mip->ra_offset = 0;
+ mip->ra_index++;
+ }
+ }
+ }
+
+out:
+ *bpp = bp;
+ return error;
+}
+