fs/xfs/xfs_dir2_readdir.c - kernel/msm-4.9 - Gitiles

 /*
  * 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_format.h"
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_bit.h"
 #include "xfs_mount.h"
 #include "xfs_da_format.h"
 #include "xfs_da_btree.h"
 #include "xfs_inode.h"
 #include "xfs_dir2.h"
 #include "xfs_dir2_priv.h"
 #include "xfs_error.h"
 #include "xfs_trace.h"
 #include "xfs_bmap.h"
 #include "xfs_trans.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,
 };

 static unsigned char
 xfs_dir3_get_dtype(
 	struct xfs_mount	*mp,
 	__uint8_t		filetype)
 {
 	if (!xfs_sb_version_hasftype(&mp->m_sb))
 		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 */
 	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_flags & XFS_IFINLINE);
 	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;

 	/*
 	 * 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.
 	 *
 	 * XXX(hch): the second argument is sometimes 0 and sometimes
 	 * geo->datablk
 	 */
 	dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
 						dp->d_ops->data_dot_offset);
 	dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
 						dp->d_ops->data_dotdot_offset);

 	/*
 	 * 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 = dp->d_ops->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 = dp->d_ops->sf_nextentry(sfp, sfep);
 			continue;
 		}

 		ino = dp->d_ops->sf_get_ino(sfp, sfep);
 		filetype = dp->d_ops->sf_get_ftype(sfep);
 		ctx->pos = off & 0x7fffffff;
 		if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
 			    xfs_dir3_get_dtype(dp->i_mount, filetype)))
 			return 0;
 		sfep = dp->d_ops->sf_nextentry(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)
 {
 	struct xfs_inode	*dp = args->dp;	/* incore directory inode */
 	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 */
 	char			*ptr;		/* current data entry */
 	int			wantoff;	/* starting block offset */
 	xfs_off_t		cook;
 	struct xfs_da_geometry	*geo = args->geo;
 	int			lock_mode;

 	/*
 	 * 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;

 	lock_mode = xfs_ilock_data_map_shared(dp);
 	error = xfs_dir3_block_read(NULL, dp, &bp);
 	xfs_iunlock(dp, lock_mode);
 	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(geo, ctx->pos);
 	hdr = bp->b_addr;
 	xfs_dir3_data_check(dp, bp);
 	/*
 	 * Set up values for the loop.
 	 */
 	btp = xfs_dir2_block_tail_p(geo, hdr);
 	ptr = (char *)dp->d_ops->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) {
 		__uint8_t filetype;

 		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 += dp->d_ops->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(geo, geo->datablk,
 					    (char *)dep - (char *)hdr);

 		ctx->pos = cook & 0x7fffffff;
 		filetype = dp->d_ops->data_get_ftype(dep);
 		/*
 		 * 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),
 			    xfs_dir3_get_dtype(dp->i_mount, filetype))) {
 			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(geo, geo->datablk + 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_da_args	*args,
 	size_t			bufsize,
 	struct xfs_dir2_leaf_map_info *mip,
 	xfs_dir2_off_t		*curoff,
 	struct xfs_buf		**bpp,
 	bool			trim_map)
 {
 	struct xfs_inode	*dp = args->dp;
 	struct xfs_buf		*bp = NULL;
 	struct xfs_bmbt_irec	*map = mip->map;
 	struct blk_plug		plug;
 	int			error = 0;
 	int			length;
 	int			i;
 	int			j;
 	struct xfs_da_geometry	*geo = args->geo;

 	/*
 	 * If the caller just finished processing a buffer, it will tell us
 	 * we need to trim that block out of the mapping now it is done.
 	 */
 	if (trim_map) {
 		mip->map_blocks -= geo->fsbcount;
 		/*
 		 * Loop to get rid of the extents for the
 		 * directory block.
 		 */
 		for (i = geo->fsbcount; 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 + geo->blksize, (1 << geo->fsblog)) - 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(geo, 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(geo, 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(geo,
 							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(geo, mip->map_off);
 		goto out;
 	}

 	/*
 	 * Read the directory block starting at the first mapping.
 	 */
 	mip->curdb = xfs_dir2_da_to_db(geo, map->br_startoff);
 	error = xfs_dir3_data_read(NULL, dp, map->br_startoff,
 			map->br_blockcount >= geo->fsbcount ?
 			    XFS_FSB_TO_DADDR(dp->i_mount, 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 -= geo->fsbcount;

 	/*
 	 * Do we need more readahead?
 	 * Each loop tries to process 1 full dir blk; last may be partial.
 	 */
 	blk_start_plug(&plug);
 	for (mip->ra_index = mip->ra_offset = i = 0;
 	     mip->ra_want > mip->ra_current && i < mip->map_blocks;
 	     i += geo->fsbcount) {
 		ASSERT(mip->ra_index < mip->map_valid);
 		/*
 		 * Read-ahead a contiguous directory block.
 		 */
 		if (i > mip->ra_current &&
 		    (map[mip->ra_index].br_blockcount - mip->ra_offset) >=
 		    geo->fsbcount) {
 			xfs_dir3_data_readahead(dp,
 				map[mip->ra_index].br_startoff + mip->ra_offset,
 				XFS_FSB_TO_DADDR(dp->i_mount,
 					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(dp,
 					map[mip->ra_index].br_startoff +
 							mip->ra_offset, -1);
 			mip->ra_current = i;
 		}

 		/*
 		 * Advance offset through the mapping table, processing a full
 		 * dir block even if it is fragmented into several extents.
 		 * But stop if we have consumed all valid mappings, even if
 		 * it's not yet a full directory block.
 		 */
 		for (j = 0;
 		     j < geo->fsbcount && mip->ra_index < mip->map_valid;
 		     j += length ) {
 			/*
 			 * The rest of this extent but not more than a dir
 			 * block.
 			 */
 			length = min_t(int, geo->fsbcount - j,
 					map[mip->ra_index].br_blockcount -
 							mip->ra_offset);
 			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(
 	struct xfs_da_args	*args,
 	struct dir_context	*ctx,
 	size_t			bufsize)
 {
 	struct xfs_inode	*dp = args->dp;
 	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 */
 	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;
 	struct xfs_da_geometry	*geo = args->geo;

 	/*
 	 * If the offset is at or past the largest allowed value,
 	 * give up right away.
 	 */
 	if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
 		return 0;

 	/*
 	 * 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 + geo->blksize, (1 << geo->fsblog));
 	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(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(geo,
 					      xfs_dir2_byte_to_db(geo, curoff));

 	/*
 	 * 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 || ptr >= (char *)bp->b_addr + geo->blksize) {
 			int	lock_mode;
 			bool	trim_map = false;

 			if (bp) {
 				xfs_trans_brelse(NULL, bp);
 				bp = NULL;
 				trim_map = true;
 			}

 			lock_mode = xfs_ilock_data_map_shared(dp);
 			error = xfs_dir2_leaf_readbuf(args, bufsize, map_info,
 						      &curoff, &bp, trim_map);
 			xfs_iunlock(dp, lock_mode);
 			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(geo,
 							 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(geo, curoff) ==
 				       map_info->curdb);
 			hdr = bp->b_addr;
 			xfs_dir3_data_check(dp, bp);
 			/*
 			 * Find our position in the block.
 			 */
 			ptr = (char *)dp->d_ops->data_entry_p(hdr);
 			byteoff = xfs_dir2_byte_to_off(geo, curoff);
 			/*
 			 * Skip past the header.
 			 */
 			if (byteoff == 0)
 				curoff += dp->d_ops->data_entry_offset;
 			/*
 			 * 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 =
 					   dp->d_ops->data_entsize(dep->namelen);
 					ptr += length;
 				}
 				/*
 				 * Now set our real offset.
 				 */
 				curoff =
 					xfs_dir2_db_off_to_byte(geo,
 					    xfs_dir2_byte_to_db(geo, curoff),
 					    (char *)ptr - (char *)hdr);
 				if (ptr >= (char *)hdr + geo->blksize) {
 					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 = dp->d_ops->data_entsize(dep->namelen);
 		filetype = dp->d_ops->data_get_ftype(dep);

 		ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
 		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.
 		 */
 		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(XFS_DIR2_MAX_DATAPTR))
 		ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
 	else
 		ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
 	kmem_free(map_info);
 	if (bp)
 		xfs_trans_brelse(NULL, bp);
 	return error;
 }

 /*
  * Read a directory.
  */
 int
 xfs_readdir(
 	struct xfs_inode	*dp,
 	struct dir_context	*ctx,
 	size_t			bufsize)
 {
 	struct xfs_da_args	args = { NULL };
 	int			rval;
 	int			v;

 	trace_xfs_readdir(dp);

 	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
 		return -EIO;

 	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
 	XFS_STATS_INC(dp->i_mount, xs_dir_getdents);

 	args.dp = dp;
 	args.geo = dp->i_mount->m_dir_geo;

 	xfs_ilock(dp, XFS_IOLOCK_SHARED);
 	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
 		rval = xfs_dir2_sf_getdents(&args, ctx);
 	else if ((rval = xfs_dir2_isblock(&args, &v)))
 		;
 	else if (v)
 		rval = xfs_dir2_block_getdents(&args, ctx);
 	else
 		rval = xfs_dir2_leaf_getdents(&args, ctx, bufsize);
 	xfs_iunlock(dp, XFS_IOLOCK_SHARED);

 	return rval;
 }
	/*
	* 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_format.h"
	#include "xfs_log_format.h"
	#include "xfs_trans_resv.h"
	#include "xfs_bit.h"
	#include "xfs_mount.h"
	#include "xfs_da_format.h"
	#include "xfs_da_btree.h"
	#include "xfs_inode.h"
	#include "xfs_dir2.h"
	#include "xfs_dir2_priv.h"
	#include "xfs_error.h"
	#include "xfs_trace.h"
	#include "xfs_bmap.h"
	#include "xfs_trans.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,
	};

	static unsigned char
	xfs_dir3_get_dtype(
	struct xfs_mount *mp,
	__uint8_t filetype)
	{
	if (!xfs_sb_version_hasftype(&mp->m_sb))
	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 */
	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_flags & XFS_IFINLINE);
	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;

	/*
	* 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.
	*
	* XXX(hch): the second argument is sometimes 0 and sometimes
	* geo->datablk
	*/
	dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
	dp->d_ops->data_dot_offset);
	dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
	dp->d_ops->data_dotdot_offset);

	/*
	* 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 = dp->d_ops->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 = dp->d_ops->sf_nextentry(sfp, sfep);
	continue;
	}

	ino = dp->d_ops->sf_get_ino(sfp, sfep);
	filetype = dp->d_ops->sf_get_ftype(sfep);
	ctx->pos = off & 0x7fffffff;
	if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
	xfs_dir3_get_dtype(dp->i_mount, filetype)))
	return 0;
	sfep = dp->d_ops->sf_nextentry(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)
	{
	struct xfs_inode dp = args->dp; / incore directory inode */
	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 */
	char ptr; / current data entry */
	int wantoff; /* starting block offset */
	xfs_off_t cook;
	struct xfs_da_geometry *geo = args->geo;
	int lock_mode;

	/*
	* 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;

	lock_mode = xfs_ilock_data_map_shared(dp);
	error = xfs_dir3_block_read(NULL, dp, &bp);
	xfs_iunlock(dp, lock_mode);
	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(geo, ctx->pos);
	hdr = bp->b_addr;
	xfs_dir3_data_check(dp, bp);
	/*
	* Set up values for the loop.
	*/
	btp = xfs_dir2_block_tail_p(geo, hdr);
	ptr = (char *)dp->d_ops->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) {
	__uint8_t filetype;

	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 += dp->d_ops->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(geo, geo->datablk,
	(char )dep - (char )hdr);

	ctx->pos = cook & 0x7fffffff;
	filetype = dp->d_ops->data_get_ftype(dep);
	/*
	* 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),
	xfs_dir3_get_dtype(dp->i_mount, filetype))) {
	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(geo, geo->datablk + 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_da_args *args,
	size_t bufsize,
	struct xfs_dir2_leaf_map_info *mip,
	xfs_dir2_off_t *curoff,
	struct xfs_buf **bpp,
	bool trim_map)
	{
	struct xfs_inode *dp = args->dp;
	struct xfs_buf *bp = NULL;
	struct xfs_bmbt_irec *map = mip->map;
	struct blk_plug plug;
	int error = 0;
	int length;
	int i;
	int j;
	struct xfs_da_geometry *geo = args->geo;

	/*
	* If the caller just finished processing a buffer, it will tell us
	* we need to trim that block out of the mapping now it is done.
	*/
	if (trim_map) {
	mip->map_blocks -= geo->fsbcount;
	/*
	* Loop to get rid of the extents for the
	* directory block.
	*/
	for (i = geo->fsbcount; 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 + geo->blksize, (1 << geo->fsblog)) - 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(geo, 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(geo, 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(geo,
	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(geo, mip->map_off);
	goto out;
	}

	/*
	* Read the directory block starting at the first mapping.
	*/
	mip->curdb = xfs_dir2_da_to_db(geo, map->br_startoff);
	error = xfs_dir3_data_read(NULL, dp, map->br_startoff,
	map->br_blockcount >= geo->fsbcount ?
	XFS_FSB_TO_DADDR(dp->i_mount, 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 -= geo->fsbcount;

	/*
	* Do we need more readahead?
	* Each loop tries to process 1 full dir blk; last may be partial.
	*/
	blk_start_plug(&plug);
	for (mip->ra_index = mip->ra_offset = i = 0;
	mip->ra_want > mip->ra_current && i < mip->map_blocks;
	i += geo->fsbcount) {
	ASSERT(mip->ra_index < mip->map_valid);
	/*
	* Read-ahead a contiguous directory block.
	*/
	if (i > mip->ra_current &&
	(map[mip->ra_index].br_blockcount - mip->ra_offset) >=
	geo->fsbcount) {
	xfs_dir3_data_readahead(dp,
	map[mip->ra_index].br_startoff + mip->ra_offset,
	XFS_FSB_TO_DADDR(dp->i_mount,
	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(dp,
	map[mip->ra_index].br_startoff +
	mip->ra_offset, -1);
	mip->ra_current = i;
	}

	/*
	* Advance offset through the mapping table, processing a full
	* dir block even if it is fragmented into several extents.
	* But stop if we have consumed all valid mappings, even if
	* it's not yet a full directory block.
	*/
	for (j = 0;
	j < geo->fsbcount && mip->ra_index < mip->map_valid;
	j += length ) {
	/*
	* The rest of this extent but not more than a dir
	* block.
	*/
	length = min_t(int, geo->fsbcount - j,
	map[mip->ra_index].br_blockcount -
	mip->ra_offset);
	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(
	struct xfs_da_args *args,
	struct dir_context *ctx,
	size_t bufsize)
	{
	struct xfs_inode *dp = args->dp;
	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 */
	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;
	struct xfs_da_geometry *geo = args->geo;

	/*
	* If the offset is at or past the largest allowed value,
	* give up right away.
	*/
	if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
	return 0;

	/*
	* 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 + geo->blksize, (1 << geo->fsblog));
	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(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(geo,
	xfs_dir2_byte_to_db(geo, curoff));

	/*
	* 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 \|\| ptr >= (char *)bp->b_addr + geo->blksize) {
	int lock_mode;
	bool trim_map = false;

	if (bp) {
	xfs_trans_brelse(NULL, bp);
	bp = NULL;
	trim_map = true;
	}

	lock_mode = xfs_ilock_data_map_shared(dp);
	error = xfs_dir2_leaf_readbuf(args, bufsize, map_info,
	&curoff, &bp, trim_map);
	xfs_iunlock(dp, lock_mode);
	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(geo,
	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(geo, curoff) ==
	map_info->curdb);
	hdr = bp->b_addr;
	xfs_dir3_data_check(dp, bp);
	/*
	* Find our position in the block.
	*/
	ptr = (char *)dp->d_ops->data_entry_p(hdr);
	byteoff = xfs_dir2_byte_to_off(geo, curoff);
	/*
	* Skip past the header.
	*/
	if (byteoff == 0)
	curoff += dp->d_ops->data_entry_offset;
	/*
	* 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 =
	dp->d_ops->data_entsize(dep->namelen);
	ptr += length;
	}
	/*
	* Now set our real offset.
	*/
	curoff =
	xfs_dir2_db_off_to_byte(geo,
	xfs_dir2_byte_to_db(geo, curoff),
	(char )ptr - (char )hdr);
	if (ptr >= (char *)hdr + geo->blksize) {
	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 = dp->d_ops->data_entsize(dep->namelen);
	filetype = dp->d_ops->data_get_ftype(dep);

	ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
	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.
	*/
	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(XFS_DIR2_MAX_DATAPTR))
	ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
	else
	ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
	kmem_free(map_info);
	if (bp)
	xfs_trans_brelse(NULL, bp);
	return error;
	}

	/*
	* Read a directory.
	*/
	int
	xfs_readdir(
	struct xfs_inode *dp,
	struct dir_context *ctx,
	size_t bufsize)
	{
	struct xfs_da_args args = { NULL };
	int rval;
	int v;

	trace_xfs_readdir(dp);

	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
	return -EIO;

	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
	XFS_STATS_INC(dp->i_mount, xs_dir_getdents);

	args.dp = dp;
	args.geo = dp->i_mount->m_dir_geo;

	xfs_ilock(dp, XFS_IOLOCK_SHARED);
	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
	rval = xfs_dir2_sf_getdents(&args, ctx);
	else if ((rval = xfs_dir2_isblock(&args, &v)))
	;
	else if (v)
	rval = xfs_dir2_block_getdents(&args, ctx);
	else
	rval = xfs_dir2_leaf_getdents(&args, ctx, bufsize);
	xfs_iunlock(dp, XFS_IOLOCK_SHARED);

	return rval;
	}