- 根目录:
- fs
- xfs
- xfs_dir2_readdir.c
/*
* 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);
/*
* 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++) {
__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)
{
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) {
__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;
lock_mode = xfs_ilock_data_map_shared(dp);
error = xfs_dir2_leaf_readbuf(args, bufsize, map_info,
&curoff, &bp);
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(dp->i_d.di_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;
}