1 files changed, 550 insertions, 0 deletions

diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
new file mode 100644
index 000000000..9f3ceb461
--- /dev/null
+++ b/fs/xfs/xfs_dir2_readdir.c
@@ -0,0 +1,550 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * Copyright (c) 2013 Red Hat, Inc.
+ * All Rights Reserved.
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_inode.h"
+#include "xfs_dir2.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_trace.h"
+#include "xfs_bmap.h"
+#include "xfs_trans.h"
+#include "xfs_error.h"
+
+/*
+ * Directory file type support functions
+ */
+static unsigned char xfs_dir3_filetype_table[] = {
+	DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK,
+	DT_FIFO, DT_SOCK, DT_LNK, DT_WHT,
+};
+
+unsigned char
+xfs_dir3_get_dtype(
+	struct xfs_mount	*mp,
+	uint8_t			filetype)
+{
+	if (!xfs_has_ftype(mp))
+		return DT_UNKNOWN;
+
+	if (filetype >= XFS_DIR3_FT_MAX)
+		return DT_UNKNOWN;
+
+	return xfs_dir3_filetype_table[filetype];
+}
+
+STATIC int
+xfs_dir2_sf_getdents(
+	struct xfs_da_args	*args,
+	struct dir_context	*ctx)
+{
+	int			i;		/* shortform entry number */
+	struct xfs_inode	*dp = args->dp;	/* incore directory inode */
+	struct xfs_mount	*mp = dp->i_mount;
+	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;
+	struct xfs_da_geometry	*geo = args->geo;
+
+	ASSERT(dp->i_df.if_format == XFS_DINODE_FMT_LOCAL);
+	ASSERT(dp->i_df.if_bytes == dp->i_disk_size);
+	ASSERT(dp->i_df.if_u1.if_data != NULL);
+
+	sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;
+
+	/*
+	 * If the block number in the offset is out of range, we're done.
+	 */
+	if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
+		return 0;
+
+	/*
+	 * Precalculate offsets for "." and ".." as we will always need them.
+	 * This relies on the fact that directories always start with the
+	 * entries for "." and "..".
+	 */
+	dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
+			geo->data_entry_offset);
+	dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
+			geo->data_entry_offset +
+			xfs_dir2_data_entsize(mp, sizeof(".") - 1));
+
+	/*
+	 * 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++) {
+		uint8_t filetype;
+
+		off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
+				xfs_dir2_sf_get_offset(sfep));
+
+		if (ctx->pos > off) {
+			sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep);
+			continue;
+		}
+
+		ino = xfs_dir2_sf_get_ino(mp, sfp, sfep);
+		filetype = xfs_dir2_sf_get_ftype(mp, sfep);
+		ctx->pos = off & 0x7fffffff;
+		if (XFS_IS_CORRUPT(dp->i_mount,
+				   !xfs_dir2_namecheck(sfep->name,
+						       sfep->namelen)))
+			return -EFSCORRUPTED;
+		if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
+			    xfs_dir3_get_dtype(mp, filetype)))
+			return 0;
+		sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep);
+	}
+
+	ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
+								0x7fffffff;
+	return 0;
+}
+
+/*
+ * Readdir for block directories.
+ */
+STATIC int
+xfs_dir2_block_getdents(
+	struct xfs_da_args	*args,
+	struct dir_context	*ctx,
+	unsigned int		*lock_mode)
+{
+	struct xfs_inode	*dp = args->dp;	/* incore directory inode */
+	struct xfs_buf		*bp;		/* buffer for block */
+	int			error;		/* error return value */
+	int			wantoff;	/* starting block offset */
+	xfs_off_t		cook;
+	struct xfs_da_geometry	*geo = args->geo;
+	unsigned int		offset, next_offset;
+	unsigned int		end;
+
+	/*
+	 * If the block number in the offset is out of range, we're done.
+	 */
+	if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
+		return 0;
+
+	error = xfs_dir3_block_read(args->trans, dp, &bp);
+	if (error)
+		return error;
+
+	xfs_iunlock(dp, *lock_mode);
+	*lock_mode = 0;
+
+	/*
+	 * Extract the byte offset we start at from the seek pointer.
+	 * We'll skip entries before this.
+	 */
+	wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos);
+	xfs_dir3_data_check(dp, bp);
+
+	/*
+	 * Loop over the data portion of the block.
+	 * Each object is a real entry (dep) or an unused one (dup).
+	 */
+	end = xfs_dir3_data_end_offset(geo, bp->b_addr);
+	for (offset = geo->data_entry_offset;
+	     offset < end;
+	     offset = next_offset) {
+		struct xfs_dir2_data_unused	*dup = bp->b_addr + offset;
+		struct xfs_dir2_data_entry	*dep = bp->b_addr + offset;
+		uint8_t filetype;
+
+		/*
+		 * Unused, skip it.
+		 */
+		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
+			next_offset = offset + be16_to_cpu(dup->length);
+			continue;
+		}
+
+		/*
+		 * Bump pointer for the next iteration.
+		 */
+		next_offset = offset +
+			xfs_dir2_data_entsize(dp->i_mount, dep->namelen);
+
+		/*
+		 * The entry is before the desired starting point, skip it.
+		 */
+		if (offset < wantoff)
+			continue;
+
+		cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, offset);
+
+		ctx->pos = cook & 0x7fffffff;
+		filetype = xfs_dir2_data_get_ftype(dp->i_mount, dep);
+		/*
+		 * If it didn't fit, set the final offset to here & return.
+		 */
+		if (XFS_IS_CORRUPT(dp->i_mount,
+				   !xfs_dir2_namecheck(dep->name,
+						       dep->namelen))) {
+			error = -EFSCORRUPTED;
+			goto out_rele;
+		}
+		if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
+			    be64_to_cpu(dep->inumber),
+			    xfs_dir3_get_dtype(dp->i_mount, filetype)))
+			goto out_rele;
+	}
+
+	/*
+	 * 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(geo, geo->datablk + 1, 0) &
+								0x7fffffff;
+out_rele:
+	xfs_trans_brelse(args->trans, bp);
+	return error;
+}
+
+/*
+ * Read a directory block and initiate readahead for blocks beyond that.
+ * We maintain a sliding readahead window of the remaining space in the
+ * buffer rounded up to the nearest block.
+ */
+STATIC int
+xfs_dir2_leaf_readbuf(
+	struct xfs_da_args	*args,
+	size_t			bufsize,
+	xfs_dir2_off_t		*cur_off,
+	xfs_dablk_t		*ra_blk,
+	struct xfs_buf		**bpp)
+{
+	struct xfs_inode	*dp = args->dp;
+	struct xfs_buf		*bp = NULL;
+	struct xfs_da_geometry	*geo = args->geo;
+	struct xfs_ifork	*ifp = xfs_ifork_ptr(dp, XFS_DATA_FORK);
+	struct xfs_bmbt_irec	map;
+	struct blk_plug		plug;
+	xfs_dir2_off_t		new_off;
+	xfs_dablk_t		next_ra;
+	xfs_dablk_t		map_off;
+	xfs_dablk_t		last_da;
+	struct xfs_iext_cursor	icur;
+	int			ra_want;
+	int			error = 0;
+
+	error = xfs_iread_extents(args->trans, dp, XFS_DATA_FORK);
+	if (error)
+		goto out;
+
+	/*
+	 * Look for mapped directory blocks at or above the current offset.
+	 * Truncate down to the nearest directory block to start the scanning
+	 * operation.
+	 */
+	last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
+	map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
+	if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
+		goto out;
+	if (map.br_startoff >= last_da)
+		goto out;
+	xfs_trim_extent(&map, map_off, last_da - map_off);
+
+	/* Read the directory block of that first mapping. */
+	new_off = xfs_dir2_da_to_byte(geo, map.br_startoff);
+	if (new_off > *cur_off)
+		*cur_off = new_off;
+	error = xfs_dir3_data_read(args->trans, dp, map.br_startoff, 0, &bp);
+	if (error)
+		goto out;
+
+	/*
+	 * Start readahead for the next bufsize's worth of dir data blocks.
+	 * We may have already issued readahead for some of that range;
+	 * ra_blk tracks the last block we tried to read(ahead).
+	 */
+	ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
+	if (*ra_blk >= last_da)
+		goto out;
+	else if (*ra_blk == 0)
+		*ra_blk = map.br_startoff;
+	next_ra = map.br_startoff + geo->fsbcount;
+	if (next_ra >= last_da)
+		goto out_no_ra;
+	if (map.br_blockcount < geo->fsbcount &&
+	    !xfs_iext_next_extent(ifp, &icur, &map))
+		goto out_no_ra;
+	if (map.br_startoff >= last_da)
+		goto out_no_ra;
+	xfs_trim_extent(&map, next_ra, last_da - next_ra);
+
+	/* Start ra for each dir (not fs) block that has a mapping. */
+	blk_start_plug(&plug);
+	while (ra_want > 0) {
+		next_ra = roundup((xfs_dablk_t)map.br_startoff, geo->fsbcount);
+		while (ra_want > 0 &&
+		       next_ra < map.br_startoff + map.br_blockcount) {
+			if (next_ra >= last_da) {
+				*ra_blk = last_da;
+				break;
+			}
+			if (next_ra > *ra_blk) {
+				xfs_dir3_data_readahead(dp, next_ra,
+							XFS_DABUF_MAP_HOLE_OK);
+				*ra_blk = next_ra;
+			}
+			ra_want -= geo->fsbcount;
+			next_ra += geo->fsbcount;
+		}
+		if (!xfs_iext_next_extent(ifp, &icur, &map)) {
+			*ra_blk = last_da;
+			break;
+		}
+	}
+	blk_finish_plug(&plug);
+
+out:
+	*bpp = bp;
+	return error;
+out_no_ra:
+	*ra_blk = last_da;
+	goto out;
+}
+
+/*
+ * 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(
+	struct xfs_da_args	*args,
+	struct dir_context	*ctx,
+	size_t			bufsize,
+	unsigned int		*lock_mode)
+{
+	struct xfs_inode	*dp = args->dp;
+	struct xfs_mount	*mp = dp->i_mount;
+	struct xfs_buf		*bp = NULL;	/* data block buffer */
+	xfs_dir2_data_entry_t	*dep;		/* data entry */
+	xfs_dir2_data_unused_t	*dup;		/* unused entry */
+	struct xfs_da_geometry	*geo = args->geo;
+	xfs_dablk_t		rablk = 0;	/* current readahead block */
+	xfs_dir2_off_t		curoff;		/* current overall offset */
+	int			length;		/* temporary length value */
+	int			byteoff;	/* offset in current block */
+	unsigned int		offset = 0;
+	int			error = 0;	/* error return value */
+
+	/*
+	 * If the offset is at or past the largest allowed value,
+	 * give up right away.
+	 */
+	if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
+		return 0;
+
+	/*
+	 * Inside the loop we keep the main offset value as a byte offset
+	 * in the directory file.
+	 */
+	curoff = xfs_dir2_dataptr_to_byte(ctx->pos);
+
+	/*
+	 * Loop over directory entries until we reach the end offset.
+	 * Get more blocks and readahead as necessary.
+	 */
+	while (curoff < XFS_DIR2_LEAF_OFFSET) {
+		uint8_t filetype;
+
+		/*
+		 * If we have no buffer, or we're off the end of the
+		 * current buffer, need to get another one.
+		 */
+		if (!bp || offset >= geo->blksize) {
+			if (bp) {
+				xfs_trans_brelse(args->trans, bp);
+				bp = NULL;
+			}
+
+			if (*lock_mode == 0)
+				*lock_mode = xfs_ilock_data_map_shared(dp);
+			error = xfs_dir2_leaf_readbuf(args, bufsize, &curoff,
+					&rablk, &bp);
+			if (error || !bp)
+				break;
+
+			xfs_iunlock(dp, *lock_mode);
+			*lock_mode = 0;
+
+			xfs_dir3_data_check(dp, bp);
+			/*
+			 * Find our position in the block.
+			 */
+			offset = geo->data_entry_offset;
+			byteoff = xfs_dir2_byte_to_off(geo, curoff);
+			/*
+			 * Skip past the header.
+			 */
+			if (byteoff == 0)
+				curoff += geo->data_entry_offset;
+			/*
+			 * Skip past entries until we reach our offset.
+			 */
+			else {
+				while (offset < byteoff) {
+					dup = bp->b_addr + offset;
+
+					if (be16_to_cpu(dup->freetag)
+						  == XFS_DIR2_DATA_FREE_TAG) {
+
+						length = be16_to_cpu(dup->length);
+						offset += length;
+						continue;
+					}
+					dep = bp->b_addr + offset;
+					length = xfs_dir2_data_entsize(mp,
+							dep->namelen);
+					offset += length;
+				}
+				/*
+				 * Now set our real offset.
+				 */
+				curoff =
+					xfs_dir2_db_off_to_byte(geo,
+					    xfs_dir2_byte_to_db(geo, curoff),
+					    offset);
+				if (offset >= geo->blksize)
+					continue;
+			}
+		}
+
+		/*
+		 * We have a pointer to an entry.  Is it a live one?
+		 */
+		dup = bp->b_addr + offset;
+
+		/*
+		 * No, it's unused, skip over it.
+		 */
+		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
+			length = be16_to_cpu(dup->length);
+			offset += length;
+			curoff += length;
+			continue;
+		}
+
+		dep = bp->b_addr + offset;
+		length = xfs_dir2_data_entsize(mp, dep->namelen);
+		filetype = xfs_dir2_data_get_ftype(mp, dep);
+
+		ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
+		if (XFS_IS_CORRUPT(dp->i_mount,
+				   !xfs_dir2_namecheck(dep->name,
+						       dep->namelen))) {
+			error = -EFSCORRUPTED;
+			break;
+		}
+		if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
+			    be64_to_cpu(dep->inumber),
+			    xfs_dir3_get_dtype(dp->i_mount, filetype)))
+			break;
+
+		/*
+		 * Advance to next entry in the block.
+		 */
+		offset += 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(XFS_DIR2_MAX_DATAPTR))
+		ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
+	else
+		ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
+	if (bp)
+		xfs_trans_brelse(args->trans, bp);
+	return error;
+}
+
+/*
+ * Read a directory.
+ *
+ * If supplied, the transaction collects locked dir buffers to avoid
+ * nested buffer deadlocks.  This function does not dirty the
+ * transaction.  The caller must hold the IOLOCK (shared or exclusive)
+ * before calling this function.
+ */
+int
+xfs_readdir(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*dp,
+	struct dir_context	*ctx,
+	size_t			bufsize)
+{
+	struct xfs_da_args	args = { NULL };
+	unsigned int		lock_mode;
+	bool			isblock;
+	int			error;
+
+	trace_xfs_readdir(dp);
+
+	if (xfs_is_shutdown(dp->i_mount))
+		return -EIO;
+
+	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
+	ASSERT(xfs_isilocked(dp, XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL));
+	XFS_STATS_INC(dp->i_mount, xs_dir_getdents);
+
+	args.dp = dp;
+	args.geo = dp->i_mount->m_dir_geo;
+	args.trans = tp;
+
+	if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL)
+		return xfs_dir2_sf_getdents(&args, ctx);
+
+	lock_mode = xfs_ilock_data_map_shared(dp);
+	error = xfs_dir2_isblock(&args, &isblock);
+	if (error)
+		goto out_unlock;
+
+	if (isblock) {
+		error = xfs_dir2_block_getdents(&args, ctx, &lock_mode);
+		goto out_unlock;
+	}
+
+	error = xfs_dir2_leaf_getdents(&args, ctx, bufsize, &lock_mode);
+
+out_unlock:
+	if (lock_mode)
+		xfs_iunlock(dp, lock_mode);
+	return error;
+}