File: [Development] / xfs-linux / xfs_rw.c (download)
Revision 1.5, Fri Mar 4 18:16:08 1994 UTC (23 years, 7 months ago) by tap
Branch: MAIN
Changes since 1.4: +1 -0
lines
rearranged order of include files: grio.h needs to be before xfs_inode.h
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#include <sys/types.h>
#ifdef SIM
#define _KERNEL 1
#endif
#include <sys/buf.h>
#include <sys/uio.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/cred.h>
#include <sys/sysmacros.h>
#include <sys/pfdat.h>
#include <sys/grio.h>
#ifdef SIM
#undef _KERNEL
#endif
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/errno.h>
#include <sys/fcntl.h>
#ifdef SIM
#include <bstring.h>
#include <stdio.h>
#else
#include <sys/conf.h>
#include <sys/systm.h>
#endif
#include <sys/kmem.h>
#include <sys/sema.h>
#include <sys/uuid.h>
#include <sys/param.h>
#include <sys/file.h>
#include "xfs_types.h"
#include "xfs_inum.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc.h"
#include "xfs_ag.h"
#include "xfs_bmap_btree.h"
#include "xfs_bmap.h"
#include "xfs_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode_item.h"
#include "xfs_inode.h"
#ifdef SIM
#include "sim.h"
#endif
/*
* This lock is used by xfs_strat_write().
*/
lock_t xfs_strat_lock;
STATIC void
xfs_zero_bp(buf_t *bp,
int data_offset,
int data_len);
STATIC int
xfs_retrieved(int available,
off_t offset,
int count,
uint *total_retrieved,
__int64_t isize);
/*
* Round the given file offset down to the nearest read/write
* size boundary.
*/
#define XFS_READIO_ALIGN(mp,off) (((off) >> mp->m_readio_log) \
<< mp->m_readio_log)
#define XFS_WRITEIO_ALIGN(mp,off) (((off) >> mp->m_writeio_log) \
<< mp->m_writeio_log)
/*
* Fill in the bmap structure to indicate how the next bp
* should fit over the given extent.
*
* Everything here is in terms of file system blocks, not BBs.
*/
void
xfs_next_bmap(xfs_mount_t *mp,
xfs_bmbt_irec_t *imapp,
struct bmapval *bmapp,
int iosize,
xfs_fsblock_t ioalign,
xfs_fsblock_t last_offset,
xfs_fsblock_t req_offset)
{
int extra_blocks;
xfs_sb_t *sbp = &mp->m_sb;
xfs_fsblock_t size_diff;
xfs_fsblock_t ext_offset;
/*
* Make sure that the request offset lies in the extent given.
*/
ASSERT(req_offset >= imapp->br_startoff);
ASSERT(req_offset < (imapp->br_startoff + imapp->br_blockcount));
if (last_offset == -1) {
ASSERT(ioalign != -1);
if (ioalign < imapp->br_startoff) {
/*
* The alignment we guessed at can't
* happen on this extent, so align
* to the beginning of this extent.
* Subtract whatever we drop from the
* iosize so that we stay aligned on
* our iosize boundaries.
*/
size_diff = imapp->br_startoff - ioalign;
iosize -= size_diff;
ASSERT(iosize > 0);
ext_offset = 0;
bmapp->offset = imapp->br_startoff;
ASSERT(bmapp->offset <= req_offset);
} else {
/*
* The alignment requested fits on this
* extent, so use it.
*/
ext_offset = ioalign - imapp->br_startoff;
bmapp->offset = ioalign;
ASSERT(bmapp->offset <= req_offset);
}
} else {
/*
* This is one of a series of sequential access to the
* file. Make sure to line up the buffer we specify
* so that it doesn't overlap the last one. It should
* either be the same as the last one (if we need data
* from it) or follow immediately after the last one.
*/
ASSERT(ioalign == -1);
if (last_offset >= imapp->br_startoff) {
/*
* The last I/O was from the same extent
* that this one will at least start on.
* This assumes that we're going sequentially.
*/
if (req_offset < (last_offset + iosize)) {
/*
* This request overlaps the buffer
* we used for the last request. Just
* get that buffer again.
*/
ext_offset = last_offset -
imapp->br_startoff;
bmapp->offset = last_offset;
} else {
/*
* This request does not overlap the buffer
* used for the last one. Get it its own.
*/
ext_offset = req_offset - imapp->br_startoff;
bmapp->offset = req_offset;
}
} else {
/*
* The last I/O was on a different extent than
* this one. We start at the beginning of this one.
* This assumes that we're going sequentially.
*/
ext_offset = 0;
bmapp->offset = req_offset;
ASSERT(bmapp->offset == imapp->br_startoff);
}
}
if ((imapp->br_startblock != DELAYSTARTBLOCK) &&
(imapp->br_startblock != HOLESTARTBLOCK)) {
bmapp->bn = imapp->br_startblock + ext_offset;
bmapp->eof = 0;
} else {
bmapp->bn = -1;
bmapp->eof = BMAP_HOLE;
}
bmapp->length = iosize;
/*
* If the iosize from our offset extends beyond the
* end of the extent, then trim down the length
* to match that of the extent.
*/
extra_blocks = (bmapp->offset + bmapp->length) -
(imapp->br_startoff + imapp->br_blockcount);
if (extra_blocks > 0) {
bmapp->length -= extra_blocks;
ASSERT(bmapp->length > 0);
}
bmapp->bsize = xfs_fsb_to_b(sbp, bmapp->length);
}
/*
* xfs_retrieved() is a utility function used to calculate the
* value of bmap.pbsize.
*
* Available is the number of bytes mapped by the current bmap.
* Offset is the file offset of the current request by the user.
* Count is the size of the current request by the user.
* Total_retrieved is a running total of the number of bytes
* which have been setup for the user in this call so far.
* eof_ok tells us whether or not to check where we are in relation
* to isize. It is used for mappings beyond the EOF generated by
* writes.
* Isize is the current size of the file being read.
*/
STATIC int
xfs_retrieved(int available,
off_t offset,
int count,
uint *total_retrieved,
__int64_t isize)
{
int retrieved;
__int64_t file_bytes_left;
if ((available + *total_retrieved) > count) {
/*
* This buffer will return more bytes
* than we asked for. Trim retrieved
* _bytes so we can set
* bmapp->pbsize correctly.
*/
retrieved = count - *total_retrieved;
} else {
retrieved = available;
}
file_bytes_left = isize - (offset + *total_retrieved);
if (file_bytes_left < retrieved) {
/*
* The user has requested more bytes
* than there are in the file. Trim
* down the number to those left in
* the file.
*/
retrieved = file_bytes_left;
}
*total_retrieved += retrieved;
return retrieved;
}
void
xfs_iomap_read(xfs_inode_t *ip,
off_t offset,
size_t count,
struct bmapval *bmapp,
int *nbmaps)
{
xfs_fsblock_t offset_fsb;
xfs_fsblock_t ioalign;
xfs_fsblock_t last_offset;
xfs_fsblock_t last_required_offset;
xfs_fsblock_t last_fsb;
xfs_fsblock_t next_offset;
__int64_t nisize;
off_t offset_page;
int nimaps;
unsigned int iosize;
unsigned int retrieved_bytes;
unsigned int total_retrieved_bytes;
short filled_bmaps;
short read_aheads;
int x;
xfs_mount_t *mp;
xfs_sb_t *sbp;
struct bmapval *curr_bmapp;
struct bmapval *next_bmapp;
struct bmapval *last_bmapp;
struct bmapval *first_read_ahead_bmapp;
struct bmapval *next_read_ahead_bmapp;
xfs_bmbt_irec_t *curr_imapp;
xfs_bmbt_irec_t *last_imapp;
#define XFS_READ_IMAPS XFS_BMAP_MAX_NMAP
xfs_bmbt_irec_t imap[XFS_READ_IMAPS];
mp = XFS_VFSTOM(XFS_ITOV(ip)->v_vfsp);
sbp = &mp->m_sb;
nisize = ip->i_new_size;
if (nisize < ip->i_d.di_size) {
nisize = ip->i_d.di_size;
}
offset_fsb = xfs_b_to_fsbt(sbp, offset);
nimaps = XFS_READ_IMAPS;
ASSERT(offset + count <= nisize);
last_fsb = xfs_b_to_fsb(sbp, nisize);
(void)xfs_bmapi(NULL, ip, offset_fsb,
(xfs_extlen_t)(last_fsb - offset_fsb),
XFS_BMAPI_ENTIRE, NULLFSBLOCK, 0, imap,
&nimaps, NULL);
if ((offset == ip->i_next_offset) &&
(count <= ip->i_last_req_sz)) {
/*
* Sequential I/O of same size as last time.
*/
ASSERT(ip->i_io_size > 0);
iosize = ip->i_io_size;
last_offset = ip->i_io_offset;
ioalign = -1;
} else {
/*
* The I/O size for the file has not yet been
* determined, so figure it out.
*/
if (xfs_b_to_fsb(sbp, count) < mp->m_readio_blocks) {
/*
* The request is smaller than our
* minimum I/O size, so default to
* the minimum. For these size requests
* we always want to align the requests
* to XFS_READ_SIZE boundaries as well.
*/
iosize = mp->m_readio_blocks;
ioalign = XFS_READIO_ALIGN(mp, offset);
ioalign = xfs_b_to_fsbt(sbp, ioalign);
} else {
/*
* The request is bigger than our
* minimum I/O size and it's the
* first one in this sequence, so
* set the I/O size for the file
* now.
*
* In calculating the offset rounded down
* to a page, make sure to round down the
* fs block offset rather than the byte
* offset for the case where our block size
* is greater than the page size. This way
* offset_page will always align to a fs block
* as well as a page.
*
* For the end of the I/O we need to round
* offset + count up to a page boundary and
* then round that up to a file system block
* boundary.
*/
offset_page = ctob(btoct(xfs_fsb_to_b(sbp,
offset_fsb)));
last_fsb = xfs_b_to_fsb(sbp,
ctob(btoc(offset + count)));
iosize = last_fsb - xfs_b_to_fsbt(sbp, offset_page);
ioalign = xfs_b_to_fsb(sbp, offset_page);
}
last_offset = -1;
}
/*
* Now we've got the I/O size and the last offset,
* so start figuring out how to align our
* buffers.
*/
xfs_next_bmap(mp, imap, bmapp, iosize, ioalign,
last_offset, offset_fsb);
ASSERT((bmapp->length > 0) &&
(offset >= xfs_fsb_to_b(sbp, bmapp->offset)));
if ((nimaps == 1) &&
(xfs_fsb_to_b(sbp, bmapp->offset + bmapp->length) >= nisize)) {
bmapp->eof |= BMAP_EOF;
}
bmapp->pboff = offset - xfs_fsb_to_b(sbp, bmapp->offset);
retrieved_bytes = bmapp->bsize - bmapp->pboff;
total_retrieved_bytes = 0;
bmapp->pbsize = xfs_retrieved(retrieved_bytes, offset, count,
&total_retrieved_bytes, nisize);
/*
* Only map additional buffers if they've been asked for
* and the I/O being done is sequential and has reached the
* point where we need to initiate more read ahead or we didn't get
* the whole request in the first bmap.
*/
filled_bmaps = 1;
last_required_offset = bmapp[0].offset;
first_read_ahead_bmapp = NULL;
if ((*nbmaps > 1) &&
(((offset == ip->i_next_offset) &&
(offset_fsb >= ip->i_reada_blkno)) ||
(retrieved_bytes < count))) {
curr_bmapp = &bmapp[0];
next_bmapp = &bmapp[1];
last_bmapp = &bmapp[*nbmaps - 1];
curr_imapp = &imap[0];
last_imapp = &imap[nimaps - 1];
/*
* curr_bmap is always the last one we filled
* in, and next_bmapp is always the next one
* to be filled in.
*/
while (next_bmapp <= last_bmapp) {
next_offset = curr_bmapp->offset +
curr_bmapp->length;
if (next_offset <
(curr_imapp->br_startoff +
curr_imapp->br_blockcount)) {
xfs_next_bmap(mp, curr_imapp,
next_bmapp, iosize, -1,
curr_bmapp->offset,
next_offset);
} else {
curr_imapp++;
if (curr_imapp <= last_imapp) {
xfs_next_bmap(mp,
curr_imapp, next_bmapp,
iosize, -1,
curr_bmapp->offset,
next_offset);
} else {
/*
* We're out of imaps. We
* either hit the end of
* file or just didn't give
* enough of them to bmapi.
* The caller will just come
* back if we haven't done
* enough yet.
*/
break;
}
}
filled_bmaps++;
curr_bmapp = next_bmapp;
next_bmapp++;
/*
* Make sure to fill in the pboff and pbsize
* fields as long as the bmaps are required for
* the request (as opposed to strictly read-ahead).
*/
if (total_retrieved_bytes < count) {
curr_bmapp->pboff = 0;
curr_bmapp->pbsize =
xfs_retrieved(curr_bmapp->bsize,
offset, count,
&total_retrieved_bytes,
nisize);
}
if ((curr_imapp == last_imapp) &&
(xfs_fsb_to_b(sbp, curr_bmapp->offset +
curr_bmapp->length) >= nisize)) {
curr_bmapp->eof |= BMAP_EOF;
}
/*
* Keep track of the offset of the last buffer
* needed to satisfy the I/O request. This will
* be used for i_io_offset later. Also record
* the first bmapp used to track a read ahead.
*/
if (xfs_fsb_to_b(sbp, curr_bmapp->offset) <
(offset + count)) {
last_required_offset = curr_bmapp->offset;
} else if (first_read_ahead_bmapp == NULL) {
first_read_ahead_bmapp = curr_bmapp;
}
}
/*
* If we're describing any read-ahead here, then move
* the read-ahead blkno up to the point where we've
* gone through half the read-ahead described here.
* This way we don't issue more read-ahead until we
* are half-way through the last read-ahead.
*
* If we're not describing any read-ahead because the
* request is just fragmented, then move up the
* read-ahead blkno to just past what we're returning
* so that we can maybe start it on the next request.
*/
if (first_read_ahead_bmapp != NULL) {
read_aheads = curr_bmapp - first_read_ahead_bmapp +1;
next_read_ahead_bmapp = first_read_ahead_bmapp +
(read_aheads / 2);
ip->i_reada_blkno = next_read_ahead_bmapp->offset;
} else {
ip->i_reada_blkno = curr_bmapp->offset +
curr_bmapp->length;
}
} else if ((*nbmaps > 1) && (offset != ip->i_io_offset)) {
/*
* In this case the caller is not yet accessing the
* file sequentially, but set the read-ahead blkno
* so that we can tell if they start doing so.
*/
ip->i_reada_blkno = bmapp[0].offset + bmapp[0].length;
}
ip->i_io_size = iosize;
ip->i_io_offset = last_required_offset;
if (count > ip->i_last_req_sz) {
/*
* Record the "last request size" for the file.
* We don't let it shrink so that big requests
* that are not satisfied in one call here still
* record the full request size (not the smaller
* one that comes in to finish mapping the request).
*/
ip->i_last_req_sz = count;
}
if (total_retrieved_bytes >= count) {
/*
* We've mapped all of the caller's request, so
* the next request in a sequential read will
* come in the block this one ended on or the
* next if we consumed up to the very end of
* a block.
*/
ip->i_next_offset = offset + count;
} else {
/*
* We didn't satisfy the entire request, so we
* can expect xfs_read_file() to come back with
* what is left of the request.
*/
ip->i_next_offset = offset + total_retrieved_bytes;
}
*nbmaps = filled_bmaps;
for (x = 0; x < filled_bmaps; x++) {
curr_bmapp = &bmapp[x];
curr_bmapp->offset = xfs_fsb_to_bb(sbp, curr_bmapp->offset);
curr_bmapp->length = xfs_fsb_to_bb(sbp, curr_bmapp->length);
if (curr_bmapp->bn != -1) {
curr_bmapp->bn =
xfs_fsb_to_daddr(sbp, curr_bmapp->bn);
}
}
return;
}
int
xfs_read_file(vnode_t *vp,
uio_t *uiop,
int ioflag,
cred_t *credp)
{
#define XFS_READ_BMAPS 4
struct bmapval bmaps[XFS_READ_BMAPS];
struct bmapval *bmapp;
int nbmaps;
buf_t *bp;
int read_bmaps;
int buffer_bytes_ok;
xfs_inode_t *ip;
int error;
ip = XFS_VTOI(vp);
error = 0;
buffer_bytes_ok = 0;
/*
* Loop until uio->uio_resid, which is the number of bytes the
* caller has requested, goes to 0 or we get an error. Each
* call to xfs_iomap_read tries to map as much of the request
* plus read-ahead as it can.
*/
do {
xfs_ilock(ip, XFS_ILOCK_SHARED);
/*
* We've fallen off the end of the file, so
* just return with what we've done so far.
*/
if (uiop->uio_offset >= ip->i_d.di_size) {
xfs_iunlock(ip, XFS_ILOCK_SHARED);
break;
}
nbmaps = XFS_READ_BMAPS;
xfs_iomap_read(ip, uiop->uio_offset, uiop->uio_resid,
bmaps, &nbmaps);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
if (error || (bmaps[0].pbsize == 0)) {
break;
}
bmapp = &bmaps[0];
read_bmaps = nbmaps;
/*
* The first time through this loop we kick off I/O on
* all the bmaps described by the iomap_read call.
* Subsequent passes just wait for each buffer needed
* to satisfy this request to complete. Buffers which
* are started in the first pass but are actually just
* read ahead buffers are never waited for, since uio_resid
* will go to 0 before we get to them.
*
* This works OK because iomap_read always tries to
* describe all the buffers we need to satisfy this
* read call plus the necessary read-ahead in the
* first call to it.
*/
while ((uiop->uio_resid != 0) && (nbmaps > 0)) {
bp = read_chunk(vp, bmapp, read_bmaps, 0, credp);
if (bp->b_flags & B_ERROR) {
error = geterror(bp);
break;
} else if (bp->b_resid != 0) {
buffer_bytes_ok = 0;
break;
} else {
buffer_bytes_ok = 1;
error = biomove(bp, bmapp->pboff,
bmapp->pbsize, UIO_READ,
uiop);
if (error) {
break;
}
}
brelse(bp);
read_bmaps = 1;
nbmaps--;
bmapp++;
}
} while (!error && (uiop->uio_resid != 0) && buffer_bytes_ok);
return error;
}
/*
* xfs_read
*
* This is a stub.
*/
int
xfs_read(vnode_t *vp,
uio_t *uiop,
int ioflag,
cred_t *credp)
{
xfs_inode_t *ip;
int type;
off_t offset;
size_t count;
int error;
ip = XFS_VTOI(vp);
ASSERT(ismrlocked(&ip->i_lock, MR_ACCESS) != 0);
type = ip->i_d.di_mode & IFMT;
ASSERT(type == IFREG || type == IFDIR ||
type == IFLNK || type == IFSOCK);
offset = uiop->uio_offset;
count = uiop->uio_resid;
#ifndef SIM
if (MANDLOCK(vp, ip->i_d.di_mode) &&
(error = chklock(vp, FREAD, offset, count, uiop->uio_fmode))) {
return error;
}
#endif
if (offset < 0)
return EINVAL;
if (count <= 0)
return 0;
switch (type) {
case IFREG:
if (ioflag & IO_DIRECT) {
error = EINVAL;
break;
}
/*
* Not ready for in-line files yet.
*/
ASSERT((ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS) ||
(ip->i_d.di_format == XFS_DINODE_FMT_BTREE));
xfs_read_file(vp, uiop, ioflag, credp);
break;
default:
ASSERT(0);
error = EINVAL;
}
return error;
}
/*
* Map the given I/O size and I/O alignment over the given extent.
* If we're at the end of the file, make sure we extend out to the
* next m_writeio_blocks boundary. Otherwise make sure that we
* are confined to the given extent.
*/
STATIC void
xfs_write_bmap(xfs_mount_t *mp,
xfs_bmbt_irec_t *imapp,
struct bmapval *bmapp,
int iosize,
xfs_fsblock_t ioalign,
__int64_t isize)
{
int extra_blocks;
xfs_sb_t *sbp = &mp->m_sb;
xfs_fsblock_t size_diff;
xfs_fsblock_t ext_offset;
off_t last_imap_byte;
if (ioalign < imapp->br_startoff) {
/*
* The desired alignment doesn't end up on this
* extent. Move up to the beginning of the extent.
* Subtract whatever we drop from the iosize so that
* we stay aligned on iosize boundaries.
*/
size_diff = imapp->br_startoff - ioalign;
iosize -= (int)size_diff;
ASSERT(iosize > 0);
ext_offset = 0;
bmapp->offset = imapp->br_startoff;
} else {
/*
* The alignment requested fits on this extent,
* so use it.
*/
ext_offset = ioalign - imapp->br_startoff;
bmapp->offset = ioalign;
}
ASSERT(imapp->br_startblock != HOLESTARTBLOCK);
if (imapp->br_startblock != DELAYSTARTBLOCK) {
bmapp->bn = imapp->br_startblock + ext_offset;
bmapp->eof = 0;
} else {
bmapp->bn = -1;
bmapp->eof = BMAP_HOLE;
}
bmapp->length = iosize;
/*
* If the iosize from our offset extends beyond the end of
* the extent and we're not at the end of the file, then trim
* down length to match that of the extent.
*/
extra_blocks = (int)((bmapp->offset + bmapp->length) -
(imapp->br_startoff + imapp->br_blockcount));
last_imap_byte = xfs_fsb_to_b(sbp, imapp->br_startoff +
imapp->br_blockcount);
if ((extra_blocks > 0) && (last_imap_byte < isize)) {
bmapp->length -= extra_blocks;
ASSERT(bmapp->length > 0);
}
bmapp->bsize = xfs_fsb_to_b(sbp, bmapp->length);
}
/*
* This routine is called to handle zeroing the buffer which overlaps
* the end of the file if the user seeks and writes beyond the EOF.
* This is necessary because those pages in the buffer which used
* to be beyond EOF and therefore invalid become valid when isize
* is extended beyond them.
*/
STATIC int
xfs_zero_eof_bp(xfs_inode_t *ip,
off_t offset,
__int64_t isize,
cred_t *credp)
{
xfs_fsblock_t last_byte_fsb;
off_t ioalign;
off_t bmap_end;
buf_t *bp;
xfs_mount_t *mp;
xfs_sb_t *sbp;
int zero_len;
int zero_offset;
int iosize;
int nimaps;
int nbmaps;
xfs_bmbt_irec_t imap;
struct bmapval bmap;
ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE) != 0);
ASSERT(offset > isize);
mp = XFS_VFSTOM(XFS_ITOV(ip)->v_vfsp);
sbp = &mp->m_sb;
iosize = mp->m_writeio_blocks;
ioalign = XFS_WRITEIO_ALIGN(mp, isize);
if (ioalign == isize) {
/*
* The buffer containing the last byte of the file
* would end at that last byte, so there is nothing
* to zero.
*/
return 0;
}
/*
* Map the space underlying the end of the file.
*/
last_byte_fsb = xfs_b_to_fsbt(sbp, isize - 1);
nimaps = 1;
(void) xfs_bmapi(NULL, ip, last_byte_fsb, 1, XFS_BMAPI_ENTIRE,
NULLFSBLOCK, 0, &imap, &nimaps, NULL);
/*
* Map a buffer over the space at the end of the file.
* Any buffer overlapping the EOF should match this one
* exactly.
*/
xfs_write_bmap(mp, &imap, &bmap, iosize, ioalign, isize);
bmap.eof |= BMAP_EOF;
xfs_iunlock(ip, XFS_ILOCK_EXCL);
bmap.offset = xfs_fsb_to_bb(sbp, bmap.offset);
bmap.length = xfs_fsb_to_bb(sbp, bmap.length);
if (bmap.bn != -1) {
bmap.bn = xfs_fsb_to_daddr(sbp, bmap.bn);
}
bp = read_chunk(XFS_ITOV(ip), &bmap, 1, 0, credp);
/*
* Zero the part of the buffer from isize to the end of
* the buffer or to where the new write will be starting.
*/
zero_offset = (int)(isize - BBTOB(bmap.offset));
bmap_end = BBTOB(bmap.offset + bmap.length);
if (bmap_end < offset) {
zero_len = bmap_end - isize;
} else {
zero_len = offset - isize;
}
#ifdef _VCE_AVOIDANCE
if (vce_avoidance) {
extern void biozero(buf_t *, uint, int);
biozero(bp, zero_offset, zero_len);
} else
#endif
{
#ifndef SIM
(void) bp_mapin(bp);
bzero(bp->b_un.b_addr + zero_offset, zero_len);
#else
xfs_zero_bp(bp, zero_offset, zero_len);
#endif /* SIM */
}
/*
* We know that there are underlying blocks from the
* beginning of the buffer to the end of the file, so
* record that fact here. Later user's of this same
* buffer will have to reset this value as they change
* the underlying file.
*/
bp->b_valid = (int)(isize - BBTOB(bmap.offset));
bdwrite(bp);
return 1;
}
STATIC void
xfs_iomap_write(xfs_inode_t *ip,
off_t offset,
size_t count,
struct bmapval *bmapp,
int *nbmaps)
{
xfs_fsblock_t offset_fsb;
xfs_fsblock_t ioalign;
xfs_fsblock_t next_offset_fsb;
xfs_fsblock_t last_fsb;
xfs_fsblock_t bmap_end_fsb;
off_t next_offset;
__int64_t isize;
xfs_extlen_t blocks;
int nimaps;
unsigned int iosize;
unsigned int writing_bytes;
int filled_bmaps;
int x;
size_t count_remaining;
xfs_mount_t *mp;
xfs_sb_t *sbp;
struct bmapval *curr_bmapp;
struct bmapval *next_bmapp;
struct bmapval *last_bmapp;
xfs_bmbt_irec_t *curr_imapp;
xfs_bmbt_irec_t *last_imapp;
#define XFS_WRITE_IMAPS XFS_BMAP_MAX_NMAP
xfs_bmbt_irec_t imap[XFS_WRITE_IMAPS];
ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE) != 0);
mp = XFS_VFSTOM(XFS_ITOV(ip)->v_vfsp);
sbp = &mp->m_sb;
isize = ip->i_d.di_size;
offset_fsb = xfs_b_to_fsbt(sbp, offset);
nimaps = XFS_WRITE_IMAPS;
last_fsb = xfs_b_to_fsb(sbp, offset + count);
blocks = (xfs_extlen_t)(last_fsb - offset_fsb);
(void) xfs_bmapi(NULL, ip, offset_fsb, blocks,
XFS_BMAPI_DELAY | XFS_BMAPI_WRITE |
XFS_BMAPI_ENTIRE, NULLFSBLOCK, blocks, imap,
&nimaps, NULL);
iosize = mp->m_writeio_blocks;
ioalign = XFS_WRITEIO_ALIGN(mp, offset);
ioalign = xfs_b_to_fsbt(sbp, ioalign);
/*
* Now map our desired I/O size and alignment over the
* extents returned by xfs_bmapi().
*/
xfs_write_bmap(mp, imap, bmapp, iosize, ioalign, isize);
ASSERT((bmapp->length > 0) &&
(offset >= xfs_fsb_to_b(sbp, bmapp->offset)));
/*
* A bmap is the EOF bmap when it reaches to or beyond the current
* inode size AND it encompasses the last block allocated to the
* file. Beyond the inode size is not good enough, because we
* could be writing more in this very request beyond what we
* are willing to describe in a single bmap.
*/
bmap_end_fsb = bmapp->offset + bmapp->length;
if ((nimaps == 1) &&
(bmap_end_fsb >= imap[0].br_startoff + imap[0].br_blockcount) &&
(xfs_fsb_to_b(sbp, bmap_end_fsb) >= isize)) {
bmapp->eof |= BMAP_EOF;
}
bmapp->pboff = offset - xfs_fsb_to_b(sbp, bmapp->offset);
writing_bytes = bmapp->bsize - bmapp->pboff;
if (writing_bytes > count) {
/*
* The mapping is for more bytes than we're actually
* going to write, so trim writing_bytes so we can
* get bmapp->pbsize right.
*/
writing_bytes = count;
}
bmapp->pbsize = writing_bytes;
/*
* Map more buffers if the first does not map the entire
* request. We do this until we run out of bmaps, imaps,
* or bytes to write.
*/
filled_bmaps = 1;
if ((*nbmaps > 1) &&
((nimaps > 1) || (bmapp->offset + bmapp->length <
imap[0].br_startoff + imap[0].br_blockcount)) &&
(writing_bytes < count)) {
curr_bmapp = &bmapp[0];
next_bmapp = &bmapp[1];
last_bmapp = &bmapp[*nbmaps - 1];
curr_imapp = &imap[0];
last_imapp = &imap[nimaps - 1];
count_remaining = count - writing_bytes;
/*
* curr_bmapp is always the last one we filled
* in, and next_bmapp is always the next one to
* be filled in.
*/
while (next_bmapp <= last_bmapp) {
next_offset_fsb = curr_bmapp->offset +
curr_bmapp->length;
if (next_offset_fsb <
(curr_imapp->br_startoff +
curr_imapp->br_blockcount)) {
/*
* I'm still on the same extent, so
* the last bmap must have ended on
* a writio_blocks boundary. Thus,
* we just start where the last one
* left off.
*/
ASSERT((xfs_fsb_to_b(sbp, next_offset_fsb) &
((1 << mp->m_writeio_log) - 1))==0);
xfs_write_bmap(mp, curr_imapp, next_bmapp,
iosize, next_offset_fsb,
isize);
} else {
curr_imapp++;
if (curr_imapp <= last_imapp) {
/*
* We're moving on to the next
* extent. Since we try to end
* all buffers on writeio_blocks
* boundaries, round next_offset
* down to a writeio_blocks boundary
* before calling xfs_write_bmap().
*
* XXXajs
* Adding a macro to writeio align
* fsblocks would be good to reduce
* the bit shifting here.
*/
ioalign = xfs_fsb_to_b(sbp,
next_offset_fsb);
ioalign = XFS_WRITEIO_ALIGN(mp,
ioalign);
ioalign = xfs_b_to_fsbt(sbp,
ioalign);
xfs_write_bmap(mp, curr_imapp,
next_bmapp, iosize,
ioalign, isize);
} else {
/*
* We're out of imaps. The caller
* will have to call again to map
* the rest of the write request.
*/
break;
}
}
/*
* The write must start at offset 0 in this bmap
* since we're just continuing from the last
* buffer. Thus the request offset in the buffer
* indicated by pboff must be 0.
*/
next_bmapp->pboff = 0;
/*
* The request size within this buffer is the
* entire buffer unless the count of bytes to
* write runs out.
*/
next_offset = xfs_fsb_to_b(sbp, next_offset_fsb);
writing_bytes = next_bmapp->bsize;
if (writing_bytes > count_remaining) {
writing_bytes = count_remaining;
}
next_bmapp->pbsize = writing_bytes;
count_remaining -= writing_bytes;
ASSERT(count_remaining >= 0);
filled_bmaps++;
curr_bmapp++;
next_bmapp++;
/*
* A bmap is the EOF bmap when it reaches to
* or beyond the current inode size AND it
* encompasses the last block allocated to the
* file. Beyond the inode size is not good
* enough, because we could be writing more
* in this very request beyond what we
* are willing to describe in a single bmap.
*/
bmap_end_fsb = curr_bmapp->offset +
curr_bmapp->length;
if ((curr_imapp == last_imapp) &&
(bmap_end_fsb >= curr_imapp->br_startoff +
curr_imapp->br_blockcount) &&
(xfs_fsb_to_b(sbp, bmap_end_fsb) >= isize)) {
curr_bmapp->eof |= BMAP_EOF;
}
}
}
*nbmaps = filled_bmaps;
for (x = 0; x < filled_bmaps; x++) {
curr_bmapp = &bmapp[x];
curr_bmapp->offset = xfs_fsb_to_bb(sbp, curr_bmapp->offset);
curr_bmapp->length = xfs_fsb_to_bb(sbp, curr_bmapp->length);
if (curr_bmapp->bn != -1) {
curr_bmapp->bn =
xfs_fsb_to_daddr(sbp, curr_bmapp->bn);
}
}
}
void
xfs_write_file(vnode_t *vp,
uio_t *uiop,
int ioflag,
cred_t *credp)
{
#define XFS_WRITE_BMAPS 4
struct bmapval bmaps[XFS_WRITE_BMAPS];
struct bmapval *bmapp;
int nbmaps;
buf_t *bp;
int buffer_bytes_ok;
xfs_inode_t *ip;
int error;
int delalloc;
int eof_zeroed;
uint valid;
uint pbcount;
off_t bp_offset;
__int64_t isize;
ip = XFS_VTOI(vp);
error = 0;
buffer_bytes_ok = 0;
eof_zeroed = 0;
/*
* i_new_size is used by xfs_iomap_read() when the chunk
* cache code calls back into the file system through
* xfs_bmap(). This way we can tell where the end of
* file is going to be even though we haven't yet updated
* ip->i_d.di_size. This is guarded by the iolock which
* is held exclusively through here.
*/
ip->i_new_size = uiop->uio_offset + uiop->uio_resid;
/*
* Loop until uiop->uio_resid, which is the number of bytes the
* caller has requested to write, goes to 0 or we get an error.
* Each call to xfs_iomap_write() tries to map as much of the
* request as it can in mp->m_writeio_blks sized chunks.
*/
do {
xfs_ilock(ip, XFS_ILOCK_EXCL);
isize = ip->i_d.di_size;
if (ip->i_new_size < isize) {
ip->i_new_size = isize;
}
/*
* If we've seeked passed the EOF to do this write,
* then we need to make sure that any buffer overlapping
* the EOF is zeroed beyond the EOF.
* xfs_zero_eof_bp() unlocks the inode lock, so make
* sure to reacquire it after the call.
*/
if (!eof_zeroed &&
(uiop->uio_offset > isize) &&
(isize != 0)) {
if (xfs_zero_eof_bp(ip, uiop->uio_offset,
isize, credp) != 0) {
xfs_ilock(ip, XFS_ILOCK_EXCL);
}
eof_zeroed = 1;
}
nbmaps = XFS_WRITE_BMAPS;
xfs_iomap_write(ip, uiop->uio_offset, uiop->uio_resid,
bmaps, &nbmaps);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
if (error || (bmaps[0].pbsize == 0)) {
break;
}
bmapp = &bmaps[0];
/*
* Each pass through the loop writes another buffer
* to the file. For big requests, iomap_write will
* have given up multiple bmaps to use so we make fewer
* calls to it on big requests than if it only gave
* us one at a time.
*/
while ((uiop->uio_resid != 0) && (nbmaps > 0)) {
/*
* If the write doesn't completely overwrite
* the buffer and we're not writing from
* the beginning of the buffer to the end
* of the file then we need to read the
* buffer.
*
* Reading the buffer will send it to xfs_strategy
* which will take care of zeroing the holey
* parts of the buffer and coordinating with
* other, simultaneous writers.
*/
if (bmapp->eof & BMAP_HOLE) {
delalloc = B_DELALLOC;
} else {
delalloc = 0;
}
if ((bmapp->pbsize != bmapp->bsize) &&
!((bmapp->pboff == 0) &&
(uiop->uio_offset >= isize))) {
bp = read_chunk(vp, bmapp, 1, delalloc,
credp);
pbcount = bmapp->pboff + bmapp->pbsize;
bp_offset = BBTOB(bmapp->offset);
if ((bp_offset + bmapp->bsize) < isize) {
/*
* The entire buffer is interior to
* the file, so the whole buffer
* is valid.
*/
valid = bmapp->bsize;
} else if ((bp_offset + pbcount) < isize)
/*
* The buffer extends past the EOF
* but we're not writing past EOF
* so up to EOF is valid.
*/
valid = isize - bp_offset;
else {
/*
* The buffer extends past the EOF
* and we're writing past EOF so
* up to where we finish writing
* is valid.
*/
valid = pbcount;
}
} else {
bp = alloc_chunk(vp, bmapp, delalloc, credp);
/*
* We're either writing the entire buffer
* or up to the EOF, so up to where we
* finish writing is valid.
*/
valid = bmapp->pboff + bmapp->pbsize;
}
/*
* XXXajs
* The error handling below needs more work.
*/
if (bp->b_flags & B_ERROR) {
error = geterror(bp);
brelse(bp);
break;
}
if (error = biomove(bp, bmapp->pboff, bmapp->pbsize,
UIO_WRITE, uiop)) {
if (!(bp->b_flags & B_DONE)) {
bp->b_flags |= B_STALE | B_DONE |
B_ERROR;
}
brelse(bp);
break;
}
/*
* Set the number of bytes in the buffer which
* are known to have been initialized. This will
* be the entire buffer except for when we have
* a buffer which extends beyond the EOF.
*/
bp->b_valid = valid;
/*
* If we've grown the file, get back the
* inode lock and move di_size up to the
* new size. It may be that someone else
* made it even bigger, so be careful not
* to shrink it.
*
* Noone could have shrunken the file, because
* we are holding the iolock shared.
*/
if (uiop->uio_offset > isize) {
xfs_ilock(ip, XFS_ILOCK_EXCL);
if (uiop->uio_offset > ip->i_d.di_size) {
ip->i_d.di_size = uiop->uio_offset;
ip->i_update_core = 1;
isize = uiop->uio_offset;
}
xfs_iunlock(ip, XFS_ILOCK_EXCL);
}
if (uiop->uio_fmode & FSYNC) {
bwrite(bp);
} else {
bdwrite(bp);
}
bmapp++;
nbmaps--;
}
} while ((uiop->uio_resid > 0) && !error);
ip->i_new_size = 0;
}
/*
* xfs_write
*
* This is a stub.
*/
int
xfs_write(vnode_t *vp,
uio_t *uiop,
int ioflag,
cred_t *credp)
{
return 0;
}
/*
* This is the xFS entry point for VOP_BMAP().
* It simply switches based on the given flags
* to either xfs_iomap_read() or xfs_iomap_write().
* This cannot be used to grow a file or to read
* beyond the end of the file.
*
* The caller is required to be holding the inode's
* iolock in at least shared mode.
*/
int
xfs_bmap(vnode_t *vp,
off_t offset,
ssize_t count,
int flags,
cred_t *credp,
struct bmapval *bmapp,
int *nbmaps)
{
xfs_inode_t *ip;
ip = XFS_VTOI(vp);
ASSERT((ip->i_d.di_mode & IFMT) == IFREG);
ASSERT(ismrlocked(&ip->i_iolock, MR_ACCESS | MR_UPDATE) != 0);
ASSERT((flags == B_READ) || (flags == B_WRITE));
if (flags == B_READ) {
xfs_ilock(ip, XFS_ILOCK_SHARED);
xfs_iomap_read(ip, offset, count, bmapp, nbmaps);
xfs_iunlock(ip, XFS_ILOCK_SHARED);
} else {
xfs_ilock(ip, XFS_ILOCK_EXCL);
ASSERT(ip->i_d.di_size >= (offset + count));
xfs_iomap_write(ip, offset, count, bmapp, nbmaps);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
}
return 0;
}
/*
* Set up rbp so that it points to the memory attached to bp
* from rbp_offset from the start of bp for rbp_len bytes.
*/
STATIC void
xfs_overlap_bp(buf_t *bp,
buf_t *rbp,
uint rbp_offset,
uint rbp_len)
{
int pgbboff;
int bytes_off;
pfd_t *pfdp;
if (BP_ISMAPPED(bp)) {
/*
* The real buffer is already mapped, so just use
* its virtual memory for ourselves.
*/
rbp->b_un.b_addr = bp->b_un.b_addr + rbp_offset;
rbp->b_bcount = rbp_len;
rbp->b_bufsize = rbp_len;
} else {
/*
* The real buffer is not yet mapped to virtual memory.
* Just get the subordinate buffer's page pointers
* set up and make it a PAGEIO buffer like the real one.
*
* First find the first page of rbp. We do this by
* walking the list of pages in bp until we find the
* one containing the start of rbp. Note that neither
* bp nor rbp are required to start on page boundaries.
*/
bytes_off = rbp_offset + BBTOB(dpoff(bp->b_offset));
pfdp = NULL;
pfdp = getnextpg(bp, pfdp);
ASSERT(pfdp != NULL);
while (bytes_off >= NBPP) {
pfdp = getnextpg(bp, pfdp);
ASSERT(pfdp != NULL);
bytes_off -= NBPP;
}
rbp->b_pages = pfdp;
rbp->b_bcount = rbp_len;
rbp->b_offset = bp->b_offset + BTOBB(rbp_offset);
pgbboff = dpoff(rbp->b_offset);
rbp->b_bufsize = ctob(dtop(pgbboff + BTOBB(rbp_len)));
rbp->b_flags |= B_PAGEIO;
#ifndef SIM
if (pgbboff != 0) {
bp_mapin(rbp);
}
#endif
}
rbp->b_blkno = bp->b_blkno + BTOBB(rbp_offset);
rbp->b_remain = 0;
rbp->b_vp = bp->b_vp;
rbp->b_edev = bp->b_edev;
rbp->b_flags |= (bp->b_flags & (B_UNCACHED | B_ASYNC));
}
/*
* Zero the given bp from data_offset from the start of it for data_len
* bytes.
*/
STATIC void
xfs_zero_bp(buf_t *bp,
int data_offset,
int data_len)
{
pfd_t *pfdp;
caddr_t page_addr;
int len;
data_offset += BBTOB(dpoff(bp->b_offset));
pfdp = NULL;
pfdp = getnextpg(bp, pfdp);
ASSERT(pfdp != NULL);
while (data_offset >= NBPP) {
pfdp = getnextpg(bp, pfdp);
ASSERT(pfdp != NULL);
data_offset -= NBPP;
}
ASSERT(data_offset >= 0);
while (data_len > 0) {
page_addr = page_mapin(pfdp, (bp->b_flags & B_UNCACHED ?
VM_UNCACHED : 0), 0);
len = MIN(data_len, NBPP - data_offset);
bzero(page_addr + data_offset, len);
data_len -= len;
data_offset = 0;
}
}
/*
* "Read" in a buffer whose b_blkno is -1. This means that
* at the time the buffer was created there was no underlying
* backing store for the range of the file covered by the bp.
* To figure out the current state of things, we lock the inode
* and call xfs_bmapi() to look at the current extents format.
* If we're over a hole or delayed allocation space we simply
* zero the corresponding portions of the buffer. For parts
* over real disk space we need to read in the stuff from disk.
*/
STATIC void
xfs_strat_read(vnode_t *vp,
buf_t *bp)
{
xfs_fsblock_t offset_fsb;
xfs_fsblock_t map_start_fsb;
xfs_fsblock_t imap_offset;
xfs_extlen_t count_fsb;
xfs_extlen_t imap_blocks;
__int64_t isize;
off_t offset;
off_t end_offset;
int x;
caddr_t datap;
buf_t *rbp;
xfs_mount_t *mp;
xfs_sb_t *sbp;
xfs_inode_t *ip;
int data_bytes;
int data_offset;
int data_len;
int nimaps;
#define XFS_STRAT_READ_IMAPS 4
xfs_bmbt_irec_t imap[XFS_STRAT_READ_IMAPS];
ASSERT(bp->b_blkno == -1);
ip = XFS_VTOI(vp);
mp = XFS_VFSTOM(vp->v_vfsp);
sbp = &mp->m_sb;
offset_fsb = xfs_bb_to_fsbt(sbp, bp->b_offset);
/*
* Only read up to the EOF.
*/
isize = ip->i_d.di_size;
offset = BBTOB(bp->b_offset);
end_offset = offset + bp->b_bcount;
if ((offset < isize) && (end_offset > isize)) {
count_fsb = xfs_b_to_fsb(sbp, isize - offset);
} else {
count_fsb = xfs_b_to_fsb(sbp, bp->b_bcount);
}
map_start_fsb = offset_fsb;
xfs_ilock(ip, XFS_ILOCK_SHARED);
while (count_fsb != 0) {
nimaps = XFS_STRAT_READ_IMAPS;
(void) xfs_bmapi(NULL, ip, map_start_fsb, count_fsb, 0,
NULLFSBLOCK, 0, imap, &nimaps, NULL);
ASSERT(nimaps >= 1);
for (x = 0; x < nimaps; x++) {
imap_offset = imap[x].br_startoff;
ASSERT(xfs_fsb_to_bb(sbp, imap_offset) ==
map_start_fsb);
imap_blocks = imap[x].br_blockcount;
ASSERT(imap_blocks <= count_fsb);
if ((imap[x].br_startblock == DELAYSTARTBLOCK) ||
(imap[x].br_startblock == HOLESTARTBLOCK)) {
/*
* This is either a hole or a delayed
* alloc extent. Either way, just fill
* it with zeroes.
*/
#ifndef SIM
datap = bp_mapin(bp);
datap += xfs_fsb_to_b(sbp, imap_offset -
offset_fsb);
data_bytes = xfs_fsb_to_b(sbp, imap_blocks);
bzero(datap, data_bytes);
#else /* SIM */
ASSERT(bp->b_flags & B_PAGEIO);
data_offset = xfs_fsb_to_b(sbp, imap_offset -
offset_fsb);
data_len = xfs_fsb_to_b(sbp, imap_blocks);
xfs_zero_bp(bp, data_offset, data_len);
#endif /* SIM */
} else {
/*
* The extent really exists on disk, so
* read it in.
*/
rbp = getrbuf(KM_SLEEP);
data_offset = xfs_fsb_to_b(sbp, imap_offset -
offset_fsb);
data_len = xfs_fsb_to_b(sbp, imap_blocks);
xfs_overlap_bp(bp, rbp, data_offset,
data_len);
rbp->b_flags |= B_READ;
rbp->b_flags &= ~B_ASYNC;
bdstrat(bmajor(rbp->b_edev), rbp);
iowait(rbp);
if (rbp->b_flags & B_ERROR) {
bp->b_flags |= B_ERROR;
bp->b_error = rbp->b_error;
}
#ifndef SIM
if (BP_ISMAPPED(rbp)) {
bp_mapout(rbp);
}
#endif
freerbuf(rbp);
}
count_fsb -= imap_blocks;
map_start_fsb += imap_blocks;
}
}
xfs_iunlock(ip, XFS_ILOCK_SHARED);
iodone(bp);
}
/*
* This is the completion routine for the heap-allocated buffers
* used to write out a buffer which becomes fragmented during
* xfs_strat_write(). It must coordinate with xfs_strat_write()
* to properly mark the lead buffer as done when necessary and
* to free the subordinate buffer.
*/
STATIC void
xfs_strat_write_relse(buf_t *rbp)
{
int s;
buf_t *leader;
buf_t *forw;
buf_t *back;
s = splockspl(xfs_strat_lock, splhi);
ASSERT(rbp->b_flags & B_DONE);
forw = (buf_t*)rbp->b_fsprivate2;
back = (buf_t*)rbp->b_fsprivate;
ASSERT(back != NULL);
/*
* Pull ourselves from the list.
*/
back->b_fsprivate2 = forw;
if (forw != NULL) {
forw->b_fsprivate = back;
}
if ((forw == NULL) &&
(back->b_flags & B_LEADER) &&
!(back->b_flags & B_PARTIAL)) {
/*
* We are the only buffer in the list and the lead buffer
* has cleared the B_PARTIAL bit to indicate that all
* subordinate buffers have been issued. That means it
* is time to finish off the lead buffer.
*/
leader = back;
if (rbp->b_flags & B_ERROR) {
leader->b_flags |= B_ERROR;
leader->b_error = rbp->b_error;
}
leader->b_flags |= B_DONE;
leader->b_flags &= ~B_LEADER;
spunlockspl(xfs_strat_lock, s);
iodone(leader);
} else {
/*
* Either there are still other buffers in the list or
* not all of the subordinate buffers have yet been issued.
* In this case just pass any errors on to the lead buffer.
*/
while (!(back->b_flags & B_LEADER)) {
back = (buf_t*)back->b_fsprivate;
}
ASSERT(back != NULL);
ASSERT(back->b_flags & B_LEADER);
leader = back;
if (rbp->b_flags & B_ERROR) {
leader->b_flags |= B_ERROR;
leader->b_error = rbp->b_error;
}
spunlockspl(xfs_strat_lock, s);
}
rbp->b_fsprivate = NULL;
rbp->b_fsprivate2 = NULL;
rbp->b_relse = NULL;
#ifndef SIM
if (BP_ISMAPPED(rbp)) {
bp_mapout(rbp);
}
#endif
freerbuf(rbp);
}
STATIC void
xfs_strat_write(vnode_t *vp,
buf_t *bp)
{
xfs_fsblock_t offset_fsb;
xfs_fsblock_t map_start_fsb;
xfs_fsblock_t imap_offset;
xfs_fsblock_t first_block;
xfs_extlen_t count_fsb;
xfs_extlen_t imap_blocks;
int x;
caddr_t datap;
buf_t *rbp;
xfs_mount_t *mp;
xfs_sb_t *sbp;
xfs_inode_t *ip;
xfs_trans_t *tp;
int error;
xfs_bmap_free_t free_list;
xfs_bmbt_irec_t *imapp;
int rbp_offset;
int rbp_len;
int set_lead = 0;
int s;
int imap_index;
int nimaps;
#define XFS_STRAT_WRITE_IMAPS 4
xfs_bmbt_irec_t imap[XFS_STRAT_WRITE_IMAPS];
ip = XFS_VTOI(vp);
mp = XFS_VFSTOM(vp->v_vfsp);
sbp = &mp->m_sb;
ASSERT((bp->b_blkno == -1) ||
(xfs_b_to_fsb(sbp, bp->b_bcount) !=
xfs_b_to_fsb(sbp, bp->b_valid)));
offset_fsb = xfs_bb_to_fsbt(sbp, bp->b_offset);
/*
* bp->b_valid tells us how many bytes are in the buffer which
* need to be written out. It will be smaller than b_bcount
* only when the buffer extends beyond the EOF.
*
* When I allow seeks beyond the EOF it will let us deal with
* the old EOF-overlapping buffers as well.
*/
ASSERT(bp->b_valid > 0);
ASSERT((BBTOB(bp->b_offset) + bp->b_valid) <= ip->i_d.di_size);
count_fsb = xfs_b_to_fsb(sbp, bp->b_valid);
map_start_fsb = offset_fsb;
bp->b_flags |= B_STALE;
while (count_fsb != 0) {
xfs_ilock(ip, XFS_ILOCK_EXCL);
/*
* Set up a transaction with which to allocate the
* backing store for the file.
*/
tp = xfs_trans_alloc(mp, XFS_TRANS_FILE_WRITE);
error = xfs_trans_reserve(tp, 0, BBTOB(128), 0, 0);
ASSERT(error == 0);
xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
xfs_trans_ihold(tp, ip);
/*
* Allocate the backing store for the file.
*/
free_list.xbf_first = NULL;
free_list.xbf_count = 0;
nimaps = XFS_STRAT_WRITE_IMAPS;
first_block = xfs_bmapi(tp, ip, map_start_fsb, count_fsb,
XFS_BMAPI_WRITE, NULLFSBLOCK, 1,
imap, &nimaps, &free_list);
ASSERT(nimaps > 0);
xfs_bmap_finish(&tp, &free_list, first_block);
xfs_trans_commit(tp, 0);
xfs_iunlock(ip, XFS_ILOCK_EXCL);
/*
* This is a quick check to see if the first time through
* was able to allocate a single extent over which to
* write
*/
if ((map_start_fsb == offset_fsb) &&
(imap[0].br_blockcount == count_fsb)) {
ASSERT(nimaps == 1);
bp->b_blkno = xfs_fsb_to_daddr(sbp,
imap[0].br_startblock);
bp->b_bcount = xfs_fsb_to_b(sbp, count_fsb);
bdstrat(bmajor(bp->b_edev), bp);
return;
}
/*
* Bmap couldn't manage to lay the buffer out as
* one extent, so we need to do multiple writes
* to push the data to the multiple extents.
* Write out the subordinate bps asynchronously
* and have their completion functions coordinate
* with the code at the end of this function to
* deal with marking our bp as done when they have
* ALL completed.
*/
imap_index = 0;
if (!set_lead) {
bp->b_flags |= B_LEADER | B_PARTIAL;
set_lead = 1;
}
while (imap_index < nimaps) {
rbp = getrbuf(KM_SLEEP);
imapp = &imap[imap_index];
imap_offset = imapp->br_startoff;
rbp_offset = xfs_fsb_to_b(sbp, imap_offset -
offset_fsb);
imap_blocks = imapp->br_blockcount;
rbp_len = xfs_fsb_to_b(sbp, imap_blocks);
xfs_overlap_bp(bp, rbp, rbp_offset, rbp_len);
/*
* Link the buffer into the list of subordinate
* buffers started at bp->b_fsprivate2. The
* subordinate buffers use b_fsprivate and
* b_fsprivate2 for back and forw pointers, but
* the lead buffer cannot use b_fsprivate.
* A subordinate buffer can always find the lead
* buffer by searching back through the fsprivate
* fields until it finds the buffer marked with
* B_LEADER.
*/
s = splockspl(xfs_strat_lock, splhi);
rbp->b_fsprivate = bp;
rbp->b_fsprivate2 = bp->b_fsprivate2;
if (bp->b_fsprivate2 != NULL) {
((buf_t*)(bp->b_fsprivate2))->b_fsprivate =
rbp;
}
bp->b_fsprivate2 = rbp;
spunlockspl(xfs_strat_lock, s);
rbp->b_relse = xfs_strat_write_relse;
bdstrat(bmajor(rbp->b_edev), rbp);
map_start_fsb += imapp->br_blockcount;
count_fsb -= imapp->br_blockcount;
ASSERT(count_fsb >= 0);
imap_index++;
}
}
/*
* Now that we've issued all the partial I/Os, check to see
* if they've all completed. If they have then mark the buffer
* as done, otherwise clear the B_PARTIAL flag in the buffer to
* indicate that the last subordinate buffer to complete should
* mark the buffer done.
*/
s = splockspl(xfs_strat_lock, splhi);
ASSERT((bp->b_flags & (B_DONE | B_PARTIAL)) == B_PARTIAL);
ASSERT(bp->b_flags & B_LEADER);
if (bp->b_fsprivate2 == NULL) {
/*
* All of the subordinate buffers have completed.
* Call iodone() to note that the I/O has completed.
*/
bp->b_flags &= ~(B_PARTIAL | B_LEADER);
spunlockspl(xfs_strat_lock, s);
iodone(bp);
return;
}
bp->b_flags &= ~B_PARTIAL;
spunlockspl(xfs_strat_lock, s);
return;
}
/*
* xfs_strategy
*
* This is where all the I/O and all the REAL allocations take
* place. For buffers with -1 for their b_blkno field, we need
* to do a bmap to figure out what to do with them. If it's a
* write we may need to do an allocation, while if it's a read
* we may either need to read from disk or do some block zeroing.
* If b_blkno specifies a real block, then all we need to do
* is pass the buffer on to the underlying driver.
*/
void
xfs_strategy(vnode_t *vp,
buf_t *bp)
{
xfs_mount_t *mp;
xfs_sb_t *sbp;
mp = XFS_VFSTOM(vp->v_vfsp);
sbp = &mp->m_sb;
/*
* If this is just a buffer whose underlying disk space
* is already allocated, then just do the requested I/O.
* b_valid equal to 0 indicates that the buffer is being read
* in by read, in which case there must be proper underlying
* disk space. Otherwise, b_valid is the number of bytes
* which we know have underlying disk space so we only want
* to do the whole buffer if the buffer size matches that.
*/
if ((bp->b_blkno > 0) &&
((bp->b_valid == 0) ||
(xfs_b_to_fsb(sbp, bp->b_bcount) ==
xfs_b_to_fsb(sbp, bp->b_valid)))) {
ASSERT((bp->b_flags & B_READ) || (bp->b_valid > 0));
bdstrat(bmajor(bp->b_edev), bp);
return;
}
/*
* If we're reading, then we need to find out how the
* portion of the file required for this buffer is layed
* out and zero/read in the appropriate data.
*/
if (bp->b_flags & B_READ) {
xfs_strat_read(vp, bp);
return;
}
/*
* Here we're writing the file and probably need to allocate
* some underlying disk space. In the real version this will
* need to queue the buffer for an xfsd if it is an ASYNC write.
* For now we'll just do the allocation regardless.
*/
if (bp->b_flags & B_ASYNC) {
/*
* Here's where we'll queue it.
*/
xfs_strat_write(vp, bp);
} else {
xfs_strat_write(vp, bp);
}
}
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