xfs: move getdents code into it's own file

The directory readdir code is not used by userspace, but it is
intermingled with files that are shared with userspace. This makes
it difficult to compare the differences between the userspac eand
kernel files are the userspace files don't have the getdents code in
them. Move all the kernel getdents code to a separate file to bring
the shared content between userspace and kernel files closer
together.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 645 insertions, 0 deletions

diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
new file mode 100644
index 000000000000..2bc4b324ff76
--- /dev/null
+++ b/fs/xfs/xfs_dir2_readdir.c
@@ -0,0 +1,645 @@
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * Copyright (c) 2013 Red Hat, Inc.
+ * All Rights Reserved.
+ *
+ * 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.
+ *
+ * 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_types.h"
+#include "xfs_bit.h"
+#include "xfs_log.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_ag.h"
+#include "xfs_mount.h"
+#include "xfs_da_btree.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_dinode.h"
+#include "xfs_inode.h"
+#include "xfs_dir2_format.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_error.h"
+#include "xfs_trace.h"
+#include "xfs_bmap.h"
+
+STATIC int
+xfs_dir2_sf_getdents(
+	xfs_inode_t		*dp,		/* incore directory inode */
+	struct dir_context	*ctx)
+{
+	int			i;		/* shortform entry number */
+	xfs_mount_t		*mp;		/* filesystem mount point */
+	xfs_dir2_dataptr_t	off;		/* current entry's offset */
+	xfs_dir2_sf_entry_t	*sfep;		/* shortform directory entry */
+	xfs_dir2_sf_hdr_t	*sfp;		/* shortform structure */
+	xfs_dir2_dataptr_t	dot_offset;
+	xfs_dir2_dataptr_t	dotdot_offset;
+	xfs_ino_t		ino;
+
+	mp = dp->i_mount;
+
+	ASSERT(dp->i_df.if_flags & XFS_IFINLINE);
+	/*
+	 * Give up if the directory is way too short.
+	 */
+	if (dp->i_d.di_size < offsetof(xfs_dir2_sf_hdr_t, parent)) {
+		ASSERT(XFS_FORCED_SHUTDOWN(mp));
+		return XFS_ERROR(EIO);
+	}
+
+	ASSERT(dp->i_df.if_bytes == dp->i_d.di_size);
+	ASSERT(dp->i_df.if_u1.if_data != NULL);
+
+	sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;
+
+	ASSERT(dp->i_d.di_size >= xfs_dir2_sf_hdr_size(sfp->i8count));
+
+	/*
+	 * If the block number in the offset is out of range, we're done.
+	 */
+	if (xfs_dir2_dataptr_to_db(mp, ctx->pos) > mp->m_dirdatablk)
+		return 0;
+
+	/*
+	 * Precalculate offsets for . and .. as we will always need them.
+	 *
+	 * XXX(hch): the second argument is sometimes 0 and sometimes
+	 * mp->m_dirdatablk.
+	 */
+	dot_offset = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
+					     XFS_DIR3_DATA_DOT_OFFSET(mp));
+	dotdot_offset = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
+						XFS_DIR3_DATA_DOTDOT_OFFSET(mp));
+
+	/*
+	 * Put . entry unless we're starting past it.
+	 */
+	if (ctx->pos <= dot_offset) {
+		ctx->pos = dot_offset & 0x7fffffff;
+		if (!dir_emit(ctx, ".", 1, dp->i_ino, DT_DIR))
+			return 0;
+	}
+
+	/*
+	 * Put .. entry unless we're starting past it.
+	 */
+	if (ctx->pos <= dotdot_offset) {
+		ino = xfs_dir2_sf_get_parent_ino(sfp);
+		ctx->pos = dotdot_offset & 0x7fffffff;
+		if (!dir_emit(ctx, "..", 2, ino, DT_DIR))
+			return 0;
+	}
+
+	/*
+	 * Loop while there are more entries and put'ing works.
+	 */
+	sfep = xfs_dir2_sf_firstentry(sfp);
+	for (i = 0; i < sfp->count; i++) {
+		off = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
+				xfs_dir2_sf_get_offset(sfep));
+
+		if (ctx->pos > off) {
+			sfep = xfs_dir2_sf_nextentry(sfp, sfep);
+			continue;
+		}
+
+		ino = xfs_dir2_sfe_get_ino(sfp, sfep);
+		ctx->pos = off & 0x7fffffff;
+		if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen,
+			    ino, DT_UNKNOWN))
+			return 0;
+		sfep = xfs_dir2_sf_nextentry(sfp, sfep);
+	}
+
+	ctx->pos = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk + 1, 0) &
+			0x7fffffff;
+	return 0;
+}
+
+/*
+ * Readdir for block directories.
+ */
+STATIC int
+xfs_dir2_block_getdents(
+	xfs_inode_t		*dp,		/* incore inode */
+	struct dir_context	*ctx)
+{
+	xfs_dir2_data_hdr_t	*hdr;		/* block header */
+	struct xfs_buf		*bp;		/* buffer for block */
+	xfs_dir2_block_tail_t	*btp;		/* block tail */
+	xfs_dir2_data_entry_t	*dep;		/* block data entry */
+	xfs_dir2_data_unused_t	*dup;		/* block unused entry */
+	char			*endptr;	/* end of the data entries */
+	int			error;		/* error return value */
+	xfs_mount_t		*mp;		/* filesystem mount point */
+	char			*ptr;		/* current data entry */
+	int			wantoff;	/* starting block offset */
+	xfs_off_t		cook;
+
+	mp = dp->i_mount;
+	/*
+	 * If the block number in the offset is out of range, we're done.
+	 */
+	if (xfs_dir2_dataptr_to_db(mp, ctx->pos) > mp->m_dirdatablk)
+		return 0;
+
+	error = xfs_dir3_block_read(NULL, dp, &bp);
+	if (error)
+		return error;
+
+	/*
+	 * Extract the byte offset we start at from the seek pointer.
+	 * We'll skip entries before this.
+	 */
+	wantoff = xfs_dir2_dataptr_to_off(mp, ctx->pos);
+	hdr = bp->b_addr;
+	xfs_dir3_data_check(dp, bp);
+	/*
+	 * Set up values for the loop.
+	 */
+	btp = xfs_dir2_block_tail_p(mp, hdr);
+	ptr = (char *)xfs_dir3_data_entry_p(hdr);
+	endptr = (char *)xfs_dir2_block_leaf_p(btp);
+
+	/*
+	 * Loop over the data portion of the block.
+	 * Each object is a real entry (dep) or an unused one (dup).
+	 */
+	while (ptr < endptr) {
+		dup = (xfs_dir2_data_unused_t *)ptr;
+		/*
+		 * Unused, skip it.
+		 */
+		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
+			ptr += be16_to_cpu(dup->length);
+			continue;
+		}
+
+		dep = (xfs_dir2_data_entry_t *)ptr;
+
+		/*
+		 * Bump pointer for the next iteration.
+		 */
+		ptr += xfs_dir2_data_entsize(dep->namelen);
+		/*
+		 * The entry is before the desired starting point, skip it.
+		 */
+		if ((char *)dep - (char *)hdr < wantoff)
+			continue;
+
+		cook = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
+					    (char *)dep - (char *)hdr);
+
+		ctx->pos = cook & 0x7fffffff;
+		/*
+		 * If it didn't fit, set the final offset to here & return.
+		 */
+		if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
+			    be64_to_cpu(dep->inumber), DT_UNKNOWN)) {
+			xfs_trans_brelse(NULL, bp);
+			return 0;
+		}
+	}
+
+	/*
+	 * Reached the end of the block.
+	 * Set the offset to a non-existent block 1 and return.
+	 */
+	ctx->pos = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk + 1, 0) &
+			0x7fffffff;
+	xfs_trans_brelse(NULL, bp);
+	return 0;
+}
+
+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;
+	struct blk_plug		plug;
+	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_dir3_data_read(NULL, dp, map->br_startoff,
+			map->br_blockcount >= mp->m_dirblkfsbs ?
+			    XFS_FSB_TO_DADDR(mp, map->br_startblock) : -1, &bp);
+
+	/*
+	 * 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?
+	 */
+	blk_start_plug(&plug);
+	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_dir3_data_readahead(NULL, dp,
+				map[mip->ra_index].br_startoff + mip->ra_offset,
+				XFS_FSB_TO_DADDR(mp,
+					map[mip->ra_index].br_startblock +
+							mip->ra_offset));
+			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_dir3_data_readahead(NULL, dp,
+					map[mip->ra_index].br_startoff +
+							mip->ra_offset, -1);
+			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++;
+			}
+		}
+	}
+	blk_finish_plug(&plug);
+
+out:
+	*bpp = bp;
+	return error;
+}
+
+/*
+ * Getdents (readdir) for leaf and node directories.
+ * This reads the data blocks only, so is the same for both forms.
+ */
+STATIC int
+xfs_dir2_leaf_getdents(
+	xfs_inode_t		*dp,		/* incore directory inode */
+	struct dir_context	*ctx,
+	size_t			bufsize)
+{
+	struct xfs_buf		*bp = NULL;	/* data block buffer */
+	xfs_dir2_data_hdr_t	*hdr;		/* data block header */
+	xfs_dir2_data_entry_t	*dep;		/* data entry */
+	xfs_dir2_data_unused_t	*dup;		/* unused entry */
+	int			error = 0;	/* error return value */
+	int			length;		/* temporary length value */
+	xfs_mount_t		*mp;		/* filesystem mount point */
+	int			byteoff;	/* offset in current block */
+	xfs_dir2_off_t		curoff;		/* current overall offset */
+	xfs_dir2_off_t		newoff;		/* new curoff after new blk */
+	char			*ptr = NULL;	/* pointer to current data */
+	struct xfs_dir2_leaf_map_info *map_info;
+
+	/*
+	 * If the offset is at or past the largest allowed value,
+	 * give up right away.
+	 */
+	if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
+		return 0;
+
+	mp = dp->i_mount;
+
+	/*
+	 * Set up to bmap a number of blocks based on the caller's
+	 * buffer size, the directory block size, and the filesystem
+	 * block size.
+	 */
+	length = howmany(bufsize + mp->m_dirblksize,
+				     mp->m_sb.sb_blocksize);
+	map_info = kmem_zalloc(offsetof(struct xfs_dir2_leaf_map_info, map) +
+				(length * sizeof(struct xfs_bmbt_irec)),
+			       KM_SLEEP | KM_NOFS);
+	map_info->map_size = length;
+
+	/*
+	 * Inside the loop we keep the main offset value as a byte offset
+	 * in the directory file.
+	 */
+	curoff = xfs_dir2_dataptr_to_byte(mp, ctx->pos);
+
+	/*
+	 * Force this conversion through db so we truncate the offset
+	 * down to get the start of the data block.
+	 */
+	map_info->map_off = xfs_dir2_db_to_da(mp,
+					      xfs_dir2_byte_to_db(mp, curoff));
+
+	/*
+	 * Loop over directory entries until we reach the end offset.
+	 * Get more blocks and readahead as necessary.
+	 */
+	while (curoff < XFS_DIR2_LEAF_OFFSET) {
+		/*
+		 * If we have no buffer, or we're off the end of the
+		 * current buffer, need to get another one.
+		 */
+		if (!bp || ptr >= (char *)bp->b_addr + mp->m_dirblksize) {
+
+			error = xfs_dir2_leaf_readbuf(dp, bufsize, map_info,
+						      &curoff, &bp);
+			if (error || !map_info->map_valid)
+				break;
+
+			/*
+			 * Having done a read, we need to set a new offset.
+			 */
+			newoff = xfs_dir2_db_off_to_byte(mp, map_info->curdb, 0);
+			/*
+			 * Start of the current block.
+			 */
+			if (curoff < newoff)
+				curoff = newoff;
+			/*
+			 * Make sure we're in the right block.
+			 */
+			else if (curoff > newoff)
+				ASSERT(xfs_dir2_byte_to_db(mp, curoff) ==
+				       map_info->curdb);
+			hdr = bp->b_addr;
+			xfs_dir3_data_check(dp, bp);
+			/*
+			 * Find our position in the block.
+			 */
+			ptr = (char *)xfs_dir3_data_entry_p(hdr);
+			byteoff = xfs_dir2_byte_to_off(mp, curoff);
+			/*
+			 * Skip past the header.
+			 */
+			if (byteoff == 0)
+				curoff += xfs_dir3_data_entry_offset(hdr);
+			/*
+			 * Skip past entries until we reach our offset.
+			 */
+			else {
+				while ((char *)ptr - (char *)hdr < byteoff) {
+					dup = (xfs_dir2_data_unused_t *)ptr;
+
+					if (be16_to_cpu(dup->freetag)
+						  == XFS_DIR2_DATA_FREE_TAG) {
+
+						length = be16_to_cpu(dup->length);
+						ptr += length;
+						continue;
+					}
+					dep = (xfs_dir2_data_entry_t *)ptr;
+					length =
+					   xfs_dir2_data_entsize(dep->namelen);
+					ptr += length;
+				}
+				/*
+				 * Now set our real offset.
+				 */
+				curoff =
+					xfs_dir2_db_off_to_byte(mp,
+					    xfs_dir2_byte_to_db(mp, curoff),
+					    (char *)ptr - (char *)hdr);
+				if (ptr >= (char *)hdr + mp->m_dirblksize) {
+					continue;
+				}
+			}
+		}
+		/*
+		 * We have a pointer to an entry.
+		 * Is it a live one?
+		 */
+		dup = (xfs_dir2_data_unused_t *)ptr;
+		/*
+		 * No, it's unused, skip over it.
+		 */
+		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
+			length = be16_to_cpu(dup->length);
+			ptr += length;
+			curoff += length;
+			continue;
+		}
+
+		dep = (xfs_dir2_data_entry_t *)ptr;
+		length = xfs_dir2_data_entsize(dep->namelen);
+
+		ctx->pos = xfs_dir2_byte_to_dataptr(mp, curoff) & 0x7fffffff;
+		if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
+			    be64_to_cpu(dep->inumber), DT_UNKNOWN))
+			break;
+
+		/*
+		 * Advance to next entry in the block.
+		 */
+		ptr += length;
+		curoff += length;
+		/* bufsize may have just been a guess; don't go negative */
+		bufsize = bufsize > length ? bufsize - length : 0;
+	}
+
+	/*
+	 * All done.  Set output offset value to current offset.
+	 */
+	if (curoff > xfs_dir2_dataptr_to_byte(mp, XFS_DIR2_MAX_DATAPTR))
+		ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
+	else
+		ctx->pos = xfs_dir2_byte_to_dataptr(mp, curoff) & 0x7fffffff;
+	kmem_free(map_info);
+	if (bp)
+		xfs_trans_brelse(NULL, bp);
+	return error;
+}
+
+/*
+ * Read a directory.
+ */
+int
+xfs_readdir(
+	xfs_inode_t	*dp,
+	struct dir_context *ctx,
+	size_t		bufsize)
+{
+	int		rval;		/* return value */
+	int		v;		/* type-checking value */
+
+	trace_xfs_readdir(dp);
+
+	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
+		return XFS_ERROR(EIO);
+
+	ASSERT(S_ISDIR(dp->i_d.di_mode));
+	XFS_STATS_INC(xs_dir_getdents);
+
+	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
+		rval = xfs_dir2_sf_getdents(dp, ctx);
+	else if ((rval = xfs_dir2_isblock(NULL, dp, &v)))
+		;
+	else if (v)
+		rval = xfs_dir2_block_getdents(dp, ctx);
+	else
+		rval = xfs_dir2_leaf_getdents(dp, ctx, bufsize);
+	return rval;
+}