/**
* @fn struct buf *getblk(int dev, bc_daddr_t blkno)
* Permet de récuperer un buffer en fonction d'un device et d'un numéro de bloc.
* S'il n'existe pas dans la table de hachage des buffers précédemment alloués, un buffer est
* retiré de la liste des buffers disponibles et alloué au device et au bloc correspondant
*
* Assign a buffer for the given block. If the appropriate
* block is already associated, return it; otherwise search
* for the oldest non-busy buffer and reassign it.
* @param dev : device (major+minor)
* @param blkno : numéro de bloc
* @return le buffer associé au device dev et de numéro de bloc blkno
*/
struct buf *getblk(int dev, bc_daddr_t blkno) {
struct buf *bp;
struct buf *dp;
loop:
dp = bhash(dev, blkno);
// Error
if (dp == NULL) {
}
for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
if (bp->b_blkno != blkno || bp->b_dev != dev) {
continue;
}
spl(BDINHB);
if (bp->b_flags & B_BUSY) {
bp->b_flags |= B_WANTED;
tsleep(PRIBIO + 1, (caddr_t) bp);
goto loop;
}
spl(NORMAL);
notavail(bp);
return bp;
}
spl(BDINHB);
if (bfreelist.av_forw == &bfreelist) {
bfreelist.b_flags |= B_WANTED;
tsleep(PRIBIO + 1, (caddr_t) &bfreelist);
goto loop;
}
spl(NORMAL);
bp = bfreelist.av_forw;
notavail(bp);
if (bp->b_flags & B_DELWRI) {
bp->b_flags |= B_ASYNC;
bwrite(bp);
goto loop;
}
bp->b_flags = B_BUSY;
bp->b_back->b_forw = bp->b_forw;
bp->b_forw->b_back = bp->b_back;
bp->b_forw = dp->b_forw;
bp->b_back = dp;
dp->b_forw->b_back = bp;
dp->b_forw = bp;
bp->b_dev = dev;
bp->b_blkno = blkno;
return bp;
}
/*
* Ensure that a specified block is up-to-date on disk.
*/
void
blkflush(dev_t dev, daddr_t blkno)
{
struct buf *bp, *dp;
struct hbuf *hp;
struct buf *sbp = NULL;
uint_t index;
kmutex_t *hmp;
index = bio_bhash(dev, blkno);
hp = &hbuf[index];
dp = (struct buf *)hp;
hmp = &hp->b_lock;
/*
* Identify the buffer in the cache belonging to
* this device and blkno (if any).
*/
mutex_enter(hmp);
for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
if (bp->b_blkno != blkno || bp->b_edev != dev ||
(bp->b_flags & B_STALE))
continue;
sbp = bp;
break;
}
mutex_exit(hmp);
if (sbp == NULL)
return;
/*
* Now check the buffer we have identified and
* make sure it still belongs to the device and is B_DELWRI
*/
sema_p(&sbp->b_sem);
if (sbp->b_blkno == blkno && sbp->b_edev == dev &&
(sbp->b_flags & (B_DELWRI|B_STALE)) == B_DELWRI) {
mutex_enter(hmp);
hp->b_length--;
notavail(sbp);
mutex_exit(hmp);
/*
* XXX - There is nothing to guarantee a synchronous
* write here if the B_ASYNC flag is set. This needs
* some investigation.
*/
if (sbp->b_vp == NULL) { /* !ufs */
BWRITE(sbp); /* synchronous write */
} else { /* ufs */
UFS_BWRITE(VTOI(sbp->b_vp)->i_ufsvfs, sbp);
}
} else {
sema_v(&sbp->b_sem);
}
}
/*
* Return a buffer w/o sleeping
*/
struct buf *
trygetblk(dev_t dev, daddr_t blkno)
{
struct buf *bp;
struct buf *dp;
struct hbuf *hp;
kmutex_t *hmp;
uint_t index;
index = bio_bhash(dev, blkno);
hp = &hbuf[index];
hmp = &hp->b_lock;
if (!mutex_tryenter(hmp))
return (NULL);
dp = (struct buf *)hp;
for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
if (bp->b_blkno != blkno || bp->b_edev != dev ||
(bp->b_flags & B_STALE))
continue;
/*
* Get access to a valid buffer without sleeping
*/
if (sema_tryp(&bp->b_sem)) {
if (bp->b_flags & B_DONE) {
hp->b_length--;
notavail(bp);
mutex_exit(hmp);
return (bp);
} else {
sema_v(&bp->b_sem);
break;
}
}
break;
}
mutex_exit(hmp);
return (NULL);
}
/*
* As part of file system hardening, this daemon is awakened
* every second to flush cached data which includes the
* buffer cache, the inode cache and mapped pages.
*/
void
fsflush()
{
struct buf *bp, *dwp;
struct hbuf *hp;
int autoup;
unsigned int ix, icount, count = 0;
callb_cpr_t cprinfo;
uint_t bcount;
kmutex_t *hmp;
struct vfssw *vswp;
proc_fsflush = ttoproc(curthread);
proc_fsflush->p_cstime = 0;
proc_fsflush->p_stime = 0;
proc_fsflush->p_cutime = 0;
proc_fsflush->p_utime = 0;
bcopy("fsflush", curproc->p_user.u_psargs, 8);
bcopy("fsflush", curproc->p_user.u_comm, 7);
mutex_init(&fsflush_lock, NULL, MUTEX_DEFAULT, NULL);
sema_init(&fsflush_sema, 0, NULL, SEMA_DEFAULT, NULL);
/*
* Setup page coalescing.
*/
fsf_npgsz = page_num_pagesizes();
ASSERT(fsf_npgsz < MAX_PAGESIZES);
for (ix = 0; ix < fsf_npgsz - 1; ++ix) {
fsf_pgcnt[ix] =
page_get_pagesize(ix + 1) / page_get_pagesize(ix);
fsf_mask[ix] = page_get_pagecnt(ix + 1) - 1;
}
autoup = v.v_autoup * hz;
icount = v.v_autoup / tune.t_fsflushr;
CALLB_CPR_INIT(&cprinfo, &fsflush_lock, callb_generic_cpr, "fsflush");
loop:
sema_v(&fsflush_sema);
mutex_enter(&fsflush_lock);
CALLB_CPR_SAFE_BEGIN(&cprinfo);
cv_wait(&fsflush_cv, &fsflush_lock); /* wait for clock */
CALLB_CPR_SAFE_END(&cprinfo, &fsflush_lock);
mutex_exit(&fsflush_lock);
sema_p(&fsflush_sema);
/*
* Write back all old B_DELWRI buffers on the freelist.
*/
bcount = 0;
for (ix = 0; ix < v.v_hbuf; ix++) {
hp = &hbuf[ix];
dwp = (struct buf *)&dwbuf[ix];
bcount += (hp->b_length);
if (dwp->av_forw == dwp) {
continue;
}
hmp = &hbuf[ix].b_lock;
mutex_enter(hmp);
bp = dwp->av_forw;
/*
* Go down only on the delayed write lists.
*/
while (bp != dwp) {
ASSERT(bp->b_flags & B_DELWRI);
if ((bp->b_flags & B_DELWRI) &&
(ddi_get_lbolt() - bp->b_start >= autoup) &&
sema_tryp(&bp->b_sem)) {
bp->b_flags |= B_ASYNC;
hp->b_length--;
notavail(bp);
mutex_exit(hmp);
if (bp->b_vp == NULL) {
BWRITE(bp);
} else {
UFS_BWRITE(VTOI(bp->b_vp)->i_ufsvfs,
bp);
}
mutex_enter(hmp);
bp = dwp->av_forw;
} else {
bp = bp->av_forw;
}
}
mutex_exit(hmp);
}
/*
*
* There is no need to wakeup any thread waiting on bio_mem_cv
* since brelse will wake them up as soon as IO is complete.
*/
bfreelist.b_bcount = bcount;
if (dopageflush)
fsflush_do_pages();
if (!doiflush)
goto loop;
/*
* If the system was not booted to single user mode, skip the
* inode flushing until after fsflush_iflush_delay secs have elapsed.
*/
if ((boothowto & RB_SINGLE) == 0 &&
(ddi_get_lbolt64() / hz) < fsflush_iflush_delay)
goto loop;
/*
* Flush cached attribute information (e.g. inodes).
*/
if (++count >= icount) {
count = 0;
/*
* Sync back cached data.
*/
RLOCK_VFSSW();
for (vswp = &vfssw[1]; vswp < &vfssw[nfstype]; vswp++) {
if (ALLOCATED_VFSSW(vswp) && VFS_INSTALLED(vswp)) {
vfs_refvfssw(vswp);
RUNLOCK_VFSSW();
(void) fsop_sync_by_kind(vswp - vfssw,
SYNC_ATTR, kcred);
vfs_unrefvfssw(vswp);
RLOCK_VFSSW();
}
}
RUNLOCK_VFSSW();
}
goto loop;
}
/*
* Make sure all write-behind blocks on dev (or NODEV for all)
* are flushed out.
*/
void
bflush(dev_t dev)
{
struct buf *bp, *dp;
struct hbuf *hp;
struct buf *delwri_list = EMPTY_LIST;
int i, index;
kmutex_t *hmp;
mutex_enter(&blist_lock);
/*
* Wait for any invalidates or flushes ahead of us to finish.
* We really could split blist_lock up per device for better
* parallelism here.
*/
while (bio_doinginval || bio_doingflush) {
bio_flinv_cv_wanted = 1;
cv_wait(&bio_flushinval_cv, &blist_lock);
}
bio_doingflush++;
/*
* Gather all B_DELWRI buffer for device.
* Lock ordering is b_sem > hash lock (brelse).
* Since we are finding the buffer via the delayed write list,
* it may be busy and we would block trying to get the
* b_sem lock while holding hash lock. So transfer all the
* candidates on the delwri_list and then drop the hash locks.
*/
for (i = 0; i < v.v_hbuf; i++) {
vfs_syncprogress();
hmp = &hbuf[i].b_lock;
dp = (struct buf *)&dwbuf[i];
mutex_enter(hmp);
for (bp = dp->av_forw; bp != dp; bp = bp->av_forw) {
if (dev == NODEV || bp->b_edev == dev) {
if (bp->b_list == NULL) {
bp->b_list = delwri_list;
delwri_list = bp;
}
}
}
mutex_exit(hmp);
}
mutex_exit(&blist_lock);
/*
* Now that the hash locks have been dropped grab the semaphores
* and write back all the buffers that have B_DELWRI set.
*/
while (delwri_list != EMPTY_LIST) {
vfs_syncprogress();
bp = delwri_list;
sema_p(&bp->b_sem); /* may block */
if ((dev != bp->b_edev && dev != NODEV) ||
(panicstr && bp->b_flags & B_BUSY)) {
sema_v(&bp->b_sem);
delwri_list = bp->b_list;
bp->b_list = NULL;
continue; /* No longer a candidate */
}
if (bp->b_flags & B_DELWRI) {
index = bio_bhash(bp->b_edev, bp->b_blkno);
hp = &hbuf[index];
hmp = &hp->b_lock;
dp = (struct buf *)hp;
bp->b_flags |= B_ASYNC;
mutex_enter(hmp);
hp->b_length--;
notavail(bp);
mutex_exit(hmp);
if (bp->b_vp == NULL) { /* !ufs */
BWRITE(bp);
} else { /* ufs */
UFS_BWRITE(VTOI(bp->b_vp)->i_ufsvfs, bp);
}
} else {
sema_v(&bp->b_sem);
}
delwri_list = bp->b_list;
bp->b_list = NULL;
}
mutex_enter(&blist_lock);
bio_doingflush--;
if (bio_flinv_cv_wanted) {
bio_flinv_cv_wanted = 0;
cv_broadcast(&bio_flushinval_cv);
}
mutex_exit(&blist_lock);
}
/*
* Assign a buffer for the given block. If the appropriate
* block is already associated, return it; otherwise search
* for the oldest non-busy buffer and reassign it.
*/
struct buf *
getblk_common(void * arg, dev_t dev, daddr_t blkno, long bsize, int errflg)
{
ufsvfs_t *ufsvfsp = (struct ufsvfs *)arg;
struct buf *bp;
struct buf *dp;
struct buf *nbp = NULL;
struct buf *errbp;
uint_t index;
kmutex_t *hmp;
struct hbuf *hp;
if (getmajor(dev) >= devcnt)
cmn_err(CE_PANIC, "blkdev");
biostats.bio_lookup.value.ui32++;
index = bio_bhash(dev, blkno);
hp = &hbuf[index];
dp = (struct buf *)hp;
hmp = &hp->b_lock;
mutex_enter(hmp);
loop:
for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
if (bp->b_blkno != blkno || bp->b_edev != dev ||
(bp->b_flags & B_STALE))
continue;
/*
* Avoid holding the hash lock in the event that
* the buffer is locked by someone. Since the hash chain
* may change when we drop the hash lock
* we have to start at the beginning of the chain if the
* buffer identity/contents aren't valid.
*/
if (!sema_tryp(&bp->b_sem)) {
biostats.bio_bufbusy.value.ui32++;
mutex_exit(hmp);
/*
* OK, we are dealing with a busy buffer.
* In the case that we are panicking and we
* got called from bread(), we have some chance
* for error recovery. So better bail out from
* here since sema_p() won't block. If we got
* called directly from ufs routines, there is
* no way to report an error yet.
*/
if (panicstr && errflg)
goto errout;
/*
* For the following line of code to work
* correctly never kmem_free the buffer "header".
*/
sema_p(&bp->b_sem);
if (bp->b_blkno != blkno || bp->b_edev != dev ||
(bp->b_flags & B_STALE)) {
sema_v(&bp->b_sem);
mutex_enter(hmp);
goto loop; /* start over */
}
mutex_enter(hmp);
}
/* Found */
biostats.bio_hit.value.ui32++;
bp->b_flags &= ~B_AGE;
/*
* Yank it off the free/delayed write lists
*/
hp->b_length--;
notavail(bp);
mutex_exit(hmp);
ASSERT((bp->b_flags & B_NOCACHE) == NULL);
if (nbp == NULL) {
/*
* Make the common path short.
*/
ASSERT(SEMA_HELD(&bp->b_sem));
return (bp);
}
biostats.bio_bufdup.value.ui32++;
/*
* The buffer must have entered during the lock upgrade
* so free the new buffer we allocated and return the
* found buffer.
*/
kmem_free(nbp->b_un.b_addr, nbp->b_bufsize);
nbp->b_un.b_addr = NULL;
/*
* Account for the memory
*/
mutex_enter(&bfree_lock);
bfreelist.b_bufsize += nbp->b_bufsize;
mutex_exit(&bfree_lock);
/*
* Destroy buf identity, and place on avail list
*/
nbp->b_dev = (o_dev_t)NODEV;
nbp->b_edev = NODEV;
nbp->b_flags = 0;
nbp->b_file = NULL;
nbp->b_offset = -1;
sema_v(&nbp->b_sem);
bio_bhdr_free(nbp);
ASSERT(SEMA_HELD(&bp->b_sem));
return (bp);
}
/*
* bio_getfreeblk may block so check the hash chain again.
*/
if (nbp == NULL) {
mutex_exit(hmp);
nbp = bio_getfreeblk(bsize);
mutex_enter(hmp);
goto loop;
}
/*
* New buffer. Assign nbp and stick it on the hash.
*/
nbp->b_flags = B_BUSY;
nbp->b_edev = dev;
nbp->b_dev = (o_dev_t)cmpdev(dev);
nbp->b_blkno = blkno;
nbp->b_iodone = NULL;
nbp->b_bcount = bsize;
/*
* If we are given a ufsvfsp and the vfs_root field is NULL
* then this must be I/O for a superblock. A superblock's
* buffer is set up in mountfs() and there is no root vnode
* at that point.
*/
if (ufsvfsp && ufsvfsp->vfs_root) {
nbp->b_vp = ufsvfsp->vfs_root;
} else {
nbp->b_vp = NULL;
}
ASSERT((nbp->b_flags & B_NOCACHE) == NULL);
binshash(nbp, dp);
mutex_exit(hmp);
ASSERT(SEMA_HELD(&nbp->b_sem));
return (nbp);
/*
* Come here in case of an internal error. At this point we couldn't
* get a buffer, but he have to return one. Hence we allocate some
* kind of error reply buffer on the fly. This buffer is marked as
* B_NOCACHE | B_AGE | B_ERROR | B_DONE to assure the following:
* - B_ERROR will indicate error to the caller.
* - B_DONE will prevent us from reading the buffer from
* the device.
* - B_NOCACHE will cause that this buffer gets free'd in
* brelse().
*/
errout:
errbp = geteblk();
sema_p(&errbp->b_sem);
errbp->b_flags &= ~B_BUSY;
errbp->b_flags |= (B_ERROR | B_DONE);
return (errbp);
}
/*
* Same as binval, except can force-invalidate delayed-write buffers
* (which are not be already flushed because of device errors). Also
* makes sure that the retry write flag is cleared.
*/
int
bfinval(dev_t dev, int force)
{
struct buf *dp;
struct buf *bp;
struct buf *binval_list = EMPTY_LIST;
int i, error = 0;
kmutex_t *hmp;
uint_t index;
struct buf **backp;
mutex_enter(&blist_lock);
/*
* Wait for any flushes ahead of us to finish, it's ok to
* do invalidates in parallel.
*/
while (bio_doingflush) {
bio_flinv_cv_wanted = 1;
cv_wait(&bio_flushinval_cv, &blist_lock);
}
bio_doinginval++;
/* Gather bp's */
for (i = 0; i < v.v_hbuf; i++) {
dp = (struct buf *)&hbuf[i];
hmp = &hbuf[i].b_lock;
mutex_enter(hmp);
for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
if (bp->b_edev == dev) {
if (bp->b_list == NULL) {
bp->b_list = binval_list;
binval_list = bp;
}
}
}
mutex_exit(hmp);
}
mutex_exit(&blist_lock);
/* Invalidate all bp's found */
while (binval_list != EMPTY_LIST) {
bp = binval_list;
sema_p(&bp->b_sem);
if (bp->b_edev == dev) {
if (force && (bp->b_flags & B_DELWRI)) {
/* clear B_DELWRI, move to non-dw freelist */
index = bio_bhash(bp->b_edev, bp->b_blkno);
hmp = &hbuf[index].b_lock;
dp = (struct buf *)&hbuf[index];
mutex_enter(hmp);
/* remove from delayed write freelist */
notavail(bp);
/* add to B_AGE side of non-dw freelist */
backp = &dp->av_forw;
(*backp)->av_back = bp;
bp->av_forw = *backp;
*backp = bp;
bp->av_back = dp;
/*
* make sure write retries and busy are cleared
*/
bp->b_flags &=
~(B_BUSY | B_DELWRI | B_RETRYWRI);
mutex_exit(hmp);
}
if ((bp->b_flags & B_DELWRI) == 0)
bp->b_flags |= B_STALE|B_AGE;
else
error = EIO;
}
sema_v(&bp->b_sem);
binval_list = bp->b_list;
bp->b_list = NULL;
}
mutex_enter(&blist_lock);
bio_doinginval--;
if (bio_flinv_cv_wanted) {
cv_broadcast(&bio_flushinval_cv);
bio_flinv_cv_wanted = 0;
}
mutex_exit(&blist_lock);
return (error);
}
