linux/fs/xfs/xfs_dir2_readdir.c

682 lines
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/*
* 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"
xfs: Add read-only support for dirent filetype field Add support for the file type field in directory entries so that readdir can return the type of the inode the dirent points to to userspace without first having to read the inode off disk. The encoding of the type field is a single byte that is added to the end of the directory entry name length. For all intents and purposes, it appends a "hidden" byte to the name field which contains the type information. As the directory entry is already of dynamic size, helpers are already required to access and decode the direct entry structures. Hence the relevent extraction and iteration helpers are updated to understand the hidden byte. Helpers for reading and writing the filetype field from the directory entries are also added. Only the read helpers are used by this patch. It also adds all the code necessary to read the type information out of the dirents on disk. Further we add the superblock feature bit and helpers to indicate that we understand the on-disk format change. This is not a compatible change - existing kernels cannot read the new format successfully - so an incompatible feature flag is added. We don't yet allow filesystems to mount with this flag yet - that will be added once write support is added. Finally, the code to take the type from the VFS, convert it to an XFS on-disk type and put it into the xfs_name structures passed around is added, but the directory code does not use this field yet. That will be in the next patch. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-08-12 12:50:09 +02:00
/*
* 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: Add read-only support for dirent filetype field Add support for the file type field in directory entries so that readdir can return the type of the inode the dirent points to to userspace without first having to read the inode off disk. The encoding of the type field is a single byte that is added to the end of the directory entry name length. For all intents and purposes, it appends a "hidden" byte to the name field which contains the type information. As the directory entry is already of dynamic size, helpers are already required to access and decode the direct entry structures. Hence the relevent extraction and iteration helpers are updated to understand the hidden byte. Helpers for reading and writing the filetype field from the directory entries are also added. Only the read helpers are used by this patch. It also adds all the code necessary to read the type information out of the dirents on disk. Further we add the superblock feature bit and helpers to indicate that we understand the on-disk format change. This is not a compatible change - existing kernels cannot read the new format successfully - so an incompatible feature flag is added. We don't yet allow filesystems to mount with this flag yet - that will be added once write support is added. Finally, the code to take the type from the VFS, convert it to an XFS on-disk type and put it into the xfs_name structures passed around is added, but the directory code does not use this field yet. That will be in the next patch. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-08-12 12:50:09 +02:00
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);
/*
* 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(dp->i_mount));
return -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(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++) {
xfs: Add read-only support for dirent filetype field Add support for the file type field in directory entries so that readdir can return the type of the inode the dirent points to to userspace without first having to read the inode off disk. The encoding of the type field is a single byte that is added to the end of the directory entry name length. For all intents and purposes, it appends a "hidden" byte to the name field which contains the type information. As the directory entry is already of dynamic size, helpers are already required to access and decode the direct entry structures. Hence the relevent extraction and iteration helpers are updated to understand the hidden byte. Helpers for reading and writing the filetype field from the directory entries are also added. Only the read helpers are used by this patch. It also adds all the code necessary to read the type information out of the dirents on disk. Further we add the superblock feature bit and helpers to indicate that we understand the on-disk format change. This is not a compatible change - existing kernels cannot read the new format successfully - so an incompatible feature flag is added. We don't yet allow filesystems to mount with this flag yet - that will be added once write support is added. Finally, the code to take the type from the VFS, convert it to an XFS on-disk type and put it into the xfs_name structures passed around is added, but the directory code does not use this field yet. That will be in the next patch. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-08-12 12:50:09 +02:00
__uint8_t filetype;
off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
xfs_dir2_sf_get_offset(sfep));
if (ctx->pos > off) {
xfs: abstract the differences in dir2/dir3 via an ops vector Lots of the dir code now goes through switches to determine what is the correct on-disk format to parse. It generally involves a "xfs_sbversion_hasfoo" check, deferencing the superblock version and feature fields and hence touching several cache lines per operation in the process. Some operations do multiple checks because they nest conditional operations and they don't pass the information in a direct fashion between each other. Hence, add an ops vector to the xfs_inode structure that is configured when the inode is initialised to point to all the correct decode and encoding operations. This will significantly reduce the branchiness and cacheline footprint of the directory object decoding and encoding. This is the first patch in a series of conversion patches. It will introduce the ops structure, the setup of it and add the first operation to the vector. Subsequent patches will convert directory ops one at a time to keep the changes simple and obvious. Just this patch shows the benefit of such an approach on code size. Just converting the two shortform dir operations as this patch does decreases the built binary size by ~1500 bytes: $ size fs/xfs/xfs.o.orig fs/xfs/xfs.o.p1 text data bss dec hex filename 794490 96802 1096 892388 d9de4 fs/xfs/xfs.o.orig 792986 96802 1096 890884 d9804 fs/xfs/xfs.o.p1 $ That's a significant decrease in the instruction cache footprint of the directory code for such a simple change, and indicates that this approach is definitely worth pursuing further. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-10-29 12:11:46 +01:00
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;
xfs: Add read-only support for dirent filetype field Add support for the file type field in directory entries so that readdir can return the type of the inode the dirent points to to userspace without first having to read the inode off disk. The encoding of the type field is a single byte that is added to the end of the directory entry name length. For all intents and purposes, it appends a "hidden" byte to the name field which contains the type information. As the directory entry is already of dynamic size, helpers are already required to access and decode the direct entry structures. Hence the relevent extraction and iteration helpers are updated to understand the hidden byte. Helpers for reading and writing the filetype field from the directory entries are also added. Only the read helpers are used by this patch. It also adds all the code necessary to read the type information out of the dirents on disk. Further we add the superblock feature bit and helpers to indicate that we understand the on-disk format change. This is not a compatible change - existing kernels cannot read the new format successfully - so an incompatible feature flag is added. We don't yet allow filesystems to mount with this flag yet - that will be added once write support is added. Finally, the code to take the type from the VFS, convert it to an XFS on-disk type and put it into the xfs_name structures passed around is added, but the directory code does not use this field yet. That will be in the next patch. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-08-12 12:50:09 +02:00
if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
xfs_dir3_get_dtype(dp->i_mount, filetype)))
return 0;
xfs: abstract the differences in dir2/dir3 via an ops vector Lots of the dir code now goes through switches to determine what is the correct on-disk format to parse. It generally involves a "xfs_sbversion_hasfoo" check, deferencing the superblock version and feature fields and hence touching several cache lines per operation in the process. Some operations do multiple checks because they nest conditional operations and they don't pass the information in a direct fashion between each other. Hence, add an ops vector to the xfs_inode structure that is configured when the inode is initialised to point to all the correct decode and encoding operations. This will significantly reduce the branchiness and cacheline footprint of the directory object decoding and encoding. This is the first patch in a series of conversion patches. It will introduce the ops structure, the setup of it and add the first operation to the vector. Subsequent patches will convert directory ops one at a time to keep the changes simple and obvious. Just this patch shows the benefit of such an approach on code size. Just converting the two shortform dir operations as this patch does decreases the built binary size by ~1500 bytes: $ size fs/xfs/xfs.o.orig fs/xfs/xfs.o.p1 text data bss dec hex filename 794490 96802 1096 892388 d9de4 fs/xfs/xfs.o.orig 792986 96802 1096 890884 d9804 fs/xfs/xfs.o.p1 $ That's a significant decrease in the instruction cache footprint of the directory code for such a simple change, and indicates that this approach is definitely worth pursuing further. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-10-29 12:11:46 +01:00
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;
/*
* 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(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(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) {
xfs: Add read-only support for dirent filetype field Add support for the file type field in directory entries so that readdir can return the type of the inode the dirent points to to userspace without first having to read the inode off disk. The encoding of the type field is a single byte that is added to the end of the directory entry name length. For all intents and purposes, it appends a "hidden" byte to the name field which contains the type information. As the directory entry is already of dynamic size, helpers are already required to access and decode the direct entry structures. Hence the relevent extraction and iteration helpers are updated to understand the hidden byte. Helpers for reading and writing the filetype field from the directory entries are also added. Only the read helpers are used by this patch. It also adds all the code necessary to read the type information out of the dirents on disk. Further we add the superblock feature bit and helpers to indicate that we understand the on-disk format change. This is not a compatible change - existing kernels cannot read the new format successfully - so an incompatible feature flag is added. We don't yet allow filesystems to mount with this flag yet - that will be added once write support is added. Finally, the code to take the type from the VFS, convert it to an XFS on-disk type and put it into the xfs_name structures passed around is added, but the directory code does not use this field yet. That will be in the next patch. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-08-12 12:50:09 +02:00
__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,
xfs: Add read-only support for dirent filetype field Add support for the file type field in directory entries so that readdir can return the type of the inode the dirent points to to userspace without first having to read the inode off disk. The encoding of the type field is a single byte that is added to the end of the directory entry name length. For all intents and purposes, it appends a "hidden" byte to the name field which contains the type information. As the directory entry is already of dynamic size, helpers are already required to access and decode the direct entry structures. Hence the relevent extraction and iteration helpers are updated to understand the hidden byte. Helpers for reading and writing the filetype field from the directory entries are also added. Only the read helpers are used by this patch. It also adds all the code necessary to read the type information out of the dirents on disk. Further we add the superblock feature bit and helpers to indicate that we understand the on-disk format change. This is not a compatible change - existing kernels cannot read the new format successfully - so an incompatible feature flag is added. We don't yet allow filesystems to mount with this flag yet - that will be added once write support is added. Finally, the code to take the type from the VFS, convert it to an XFS on-disk type and put it into the xfs_name structures passed around is added, but the directory code does not use this field yet. That will be in the next patch. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-08-12 12:50:09 +02:00
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)
{
struct xfs_inode *dp = args->dp;
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;
struct xfs_da_geometry *geo = args->geo;
/*
* 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 -= 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?
*/
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 >= 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.
*/
for (j = 0; j < geo->fsbcount; j += length ) {
/*
* The rest of this extent but not more than a dir
* block.
*/
length = min_t(int, geo->fsbcount,
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) {
xfs: Add read-only support for dirent filetype field Add support for the file type field in directory entries so that readdir can return the type of the inode the dirent points to to userspace without first having to read the inode off disk. The encoding of the type field is a single byte that is added to the end of the directory entry name length. For all intents and purposes, it appends a "hidden" byte to the name field which contains the type information. As the directory entry is already of dynamic size, helpers are already required to access and decode the direct entry structures. Hence the relevent extraction and iteration helpers are updated to understand the hidden byte. Helpers for reading and writing the filetype field from the directory entries are also added. Only the read helpers are used by this patch. It also adds all the code necessary to read the type information out of the dirents on disk. Further we add the superblock feature bit and helpers to indicate that we understand the on-disk format change. This is not a compatible change - existing kernels cannot read the new format successfully - so an incompatible feature flag is added. We don't yet allow filesystems to mount with this flag yet - that will be added once write support is added. Finally, the code to take the type from the VFS, convert it to an XFS on-disk type and put it into the xfs_name structures passed around is added, but the directory code does not use this field yet. That will be in the next patch. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-08-12 12:50:09 +02:00
__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) {
error = xfs_dir2_leaf_readbuf(args, 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(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,
xfs: Add read-only support for dirent filetype field Add support for the file type field in directory entries so that readdir can return the type of the inode the dirent points to to userspace without first having to read the inode off disk. The encoding of the type field is a single byte that is added to the end of the directory entry name length. For all intents and purposes, it appends a "hidden" byte to the name field which contains the type information. As the directory entry is already of dynamic size, helpers are already required to access and decode the direct entry structures. Hence the relevent extraction and iteration helpers are updated to understand the hidden byte. Helpers for reading and writing the filetype field from the directory entries are also added. Only the read helpers are used by this patch. It also adds all the code necessary to read the type information out of the dirents on disk. Further we add the superblock feature bit and helpers to indicate that we understand the on-disk format change. This is not a compatible change - existing kernels cannot read the new format successfully - so an incompatible feature flag is added. We don't yet allow filesystems to mount with this flag yet - that will be added once write support is added. Finally, the code to take the type from the VFS, convert it to an XFS on-disk type and put it into the xfs_name structures passed around is added, but the directory code does not use this field yet. That will be in the next patch. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
2013-08-12 12:50:09 +02:00
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;
uint lock_mode;
trace_xfs_readdir(dp);
if (XFS_FORCED_SHUTDOWN(dp->i_mount))
return -EIO;
ASSERT(S_ISDIR(dp->i_d.di_mode));
XFS_STATS_INC(xs_dir_getdents);
args.dp = dp;
args.geo = dp->i_mount->m_dir_geo;
lock_mode = xfs_ilock_data_map_shared(dp);
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, lock_mode);
return rval;
}