#include <afsconfig.h>
#include "afs/param.h"
-RCSID
- ("$Header$");
#include "afs/sysincludes.h"
#include "afsincludes.h"
#ifndef BUF_TIME_MAX
#define BUF_TIME_MAX 0x7fffffff
#endif
+#if defined(AFS_USEBUFFERS)
/* number of pages per Unix buffer, when we're using Unix buffer pool */
-#define NPB 4
+#define NPB 4
+#else
+#define NPB 8 /* must be a pwer of 2 */
+#endif
+static int afs_max_buffers; /* should be an integral multiple of NPB */
+
/* page size */
#define AFS_BUFFER_PAGESIZE 2048
/* log page size */
#ifdef AFS_FBSD_ENV
#define timecounter afs_timecounter
#endif
-/* The locks for individual buffer entries are now sometimes obtained while holding the
- * afs_bufferLock. Thus we now have a locking hierarchy: afs_bufferLock -> Buffers[].lock.
+
+/* A note on locking in 'struct buffer'
+ *
+ * afs_bufferLock protects the hash chain, and the 'lockers' field where that
+ * has a zero value. It must be held whenever lockers is incremented from zero.
+ *
+ * The individual buffer lock protects the contents of the structure, including
+ * the lockers field.
+ *
+ * For safety: afs_bufferLock and the individual buffer lock must be held
+ * when obtaining a reference on a structure. Only the individual buffer lock
+ * need be held when releasing a reference.
+ *
+ * The locking hierarchy is afs_bufferLock-> buffer.lock
+ *
*/
+
static afs_lock_t afs_bufferLock;
static struct buffer *phTable[PHSIZE]; /* page hash table */
static int nbuffers;
if (dinit_flag)
return;
dinit_flag = 1;
-#if defined(AFS_USEBUFFERS)
/* round up to next multiple of NPB, since we allocate multiple pages per chunk */
abuffers = ((abuffers - 1) | (NPB - 1)) + 1;
+#if defined(AFS_USEBUFFERS)
+ afs_max_buffers = abuffers;
+#else
+ afs_max_buffers = abuffers << 2; /* possibly grow up to 4 times as big */
#endif
LOCK_INIT(&afs_bufferLock, "afs_bufferLock");
Buffers =
- (struct buffer *)afs_osi_Alloc(abuffers * sizeof(struct buffer));
-#if !defined(AFS_USEBUFFERS)
- BufferData = (char *)afs_osi_Alloc(abuffers * AFS_BUFFER_PAGESIZE);
-#endif
+ (struct buffer *)afs_osi_Alloc(afs_max_buffers * sizeof(struct buffer));
timecounter = 1;
afs_stats_cmperf.bufAlloced = nbuffers = abuffers;
for (i = 0; i < PHSIZE; i++)
phTable[i] = 0;
for (i = 0; i < abuffers; i++) {
-#if defined(AFS_USEBUFFERS)
if ((i & (NPB - 1)) == 0) {
/* time to allocate a fresh buffer */
+#if defined(AFS_USEBUFFERS)
tub = geteblk(AFS_BUFFER_PAGESIZE * NPB);
BufferData = (char *)tub->b_un.b_addr;
- }
+#else
+ BufferData = (char *) afs_osi_Alloc(AFS_BUFFER_PAGESIZE * NPB);
#endif
+ }
/* Fill in each buffer with an empty indication. */
tb = &Buffers[i];
tb->fid = NULLIDX;
- tb->inode = 0;
+ afs_reset_inode(&tb->inode);
tb->accesstime = 0;
tb->lockers = 0;
#if defined(AFS_USEBUFFERS)
tb->bufp = tub;
else
tb->bufp = 0;
- tb->data = &BufferData[AFS_BUFFER_PAGESIZE * (i & (NPB - 1))];
-#else
- tb->data = &BufferData[AFS_BUFFER_PAGESIZE * i];
#endif
+ tb->data = &BufferData[AFS_BUFFER_PAGESIZE * (i & (NPB - 1))];
tb->hashIndex = 0;
tb->dirty = 0;
- RWLOCK_INIT(&tb->lock, "buffer lock");
+ AFS_RWLOCK_INIT(&tb->lock, "buffer lock");
}
return;
}
int code;
AFS_STATCNT(DRead);
- MObtainWriteLock(&afs_bufferLock, 256);
+ ObtainWriteLock(&afs_bufferLock, 256);
#define bufmatch(tb) (tb->page == page && tb->fid == adc->index)
#define buf_Front(head,parent,p) {(parent)->hashNext = (p)->hashNext; (p)->hashNext= *(head);*(head)=(p);}
*/
if ((tb = phTable[pHash(adc->index, page)])) {
if (bufmatch(tb)) {
- MObtainWriteLock(&tb->lock, 257);
- ReleaseWriteLock(&afs_bufferLock);
+ ObtainWriteLock(&tb->lock, 257);
tb->lockers++;
+ ReleaseWriteLock(&afs_bufferLock);
tb->accesstime = timecounter++;
AFS_STATS(afs_stats_cmperf.bufHits++);
- MReleaseWriteLock(&tb->lock);
+ ReleaseWriteLock(&tb->lock);
return tb->data;
} else {
register struct buffer **bufhead;
while ((tb2 = tb->hashNext)) {
if (bufmatch(tb2)) {
buf_Front(bufhead, tb, tb2);
- MObtainWriteLock(&tb2->lock, 258);
- ReleaseWriteLock(&afs_bufferLock);
+ ObtainWriteLock(&tb2->lock, 258);
tb2->lockers++;
+ ReleaseWriteLock(&afs_bufferLock);
tb2->accesstime = timecounter++;
AFS_STATS(afs_stats_cmperf.bufHits++);
- MReleaseWriteLock(&tb2->lock);
+ ReleaseWriteLock(&tb2->lock);
return tb2->data;
}
if ((tb = tb2->hashNext)) {
if (bufmatch(tb)) {
buf_Front(bufhead, tb2, tb);
- MObtainWriteLock(&tb->lock, 259);
- ReleaseWriteLock(&afs_bufferLock);
+ ObtainWriteLock(&tb->lock, 259);
tb->lockers++;
+ ReleaseWriteLock(&afs_bufferLock);
tb->accesstime = timecounter++;
AFS_STATS(afs_stats_cmperf.bufHits++);
- MReleaseWriteLock(&tb->lock);
+ ReleaseWriteLock(&tb->lock);
return tb->data;
}
} else
*/
tb = afs_newslot(adc, page, (tb ? tb : tb2));
if (!tb) {
- MReleaseWriteLock(&afs_bufferLock);
+ ReleaseWriteLock(&afs_bufferLock);
return NULL;
}
- MObtainWriteLock(&tb->lock, 260);
- MReleaseWriteLock(&afs_bufferLock);
+ ObtainWriteLock(&tb->lock, 260);
tb->lockers++;
+ ReleaseWriteLock(&afs_bufferLock);
if (page * AFS_BUFFER_PAGESIZE >= adc->f.chunkBytes) {
tb->fid = NULLIDX;
- tb->inode = 0;
+ afs_reset_inode(&tb->inode);
tb->lockers--;
- MReleaseWriteLock(&tb->lock);
+ ReleaseWriteLock(&tb->lock);
return NULL;
}
- tfile = afs_CFileOpen(adc->f.inode);
+ tfile = afs_CFileOpen(&adc->f.inode);
code =
afs_CFileRead(tfile, tb->page * AFS_BUFFER_PAGESIZE, tb->data,
AFS_BUFFER_PAGESIZE);
afs_CFileClose(tfile);
if (code < AFS_BUFFER_PAGESIZE) {
tb->fid = NULLIDX;
- tb->inode = 0;
+ afs_reset_inode(&tb->inode);
tb->lockers--;
- MReleaseWriteLock(&tb->lock);
+ ReleaseWriteLock(&tb->lock);
return NULL;
}
/* Note that findslot sets the page field in the buffer equal to
* what it is searching for. */
- MReleaseWriteLock(&tb->lock);
+ ReleaseWriteLock(&tb->lock);
return tb->data;
}
{
/* Find a usable buffer slot */
register afs_int32 i;
- afs_int32 lt;
+ afs_int32 lt = 0;
register struct buffer *tp;
struct osi_file *tfile;
if (lp && (lp->lockers == 0)) {
lt = lp->accesstime;
} else {
- lp = 0;
- lt = BUF_TIME_MAX;
+ lp = NULL;
}
/* timecounter might have wrapped, if machine is very very busy
tp = Buffers;
for (i = 0; i < nbuffers; i++, tp++) {
if (tp->lockers == 0) {
- if (tp->accesstime < lt) {
+ if (!lp || tp->accesstime < lt) {
lp = tp;
lt = tp->accesstime;
}
}
if (lp == 0) {
- /* There are no unlocked buffers -- this used to panic, but that
- * seems extreme. To the best of my knowledge, all the callers
- * of DRead are prepared to handle a zero return. Some of them
- * just panic directly, but not all of them. */
- afs_warn("all buffers locked");
- return 0;
+ /* No unlocked buffers. If still possible, allocate a new increment */
+ if (nbuffers + NPB > afs_max_buffers) {
+ /* There are no unlocked buffers -- this used to panic, but that
+ * seems extreme. To the best of my knowledge, all the callers
+ * of DRead are prepared to handle a zero return. Some of them
+ * just panic directly, but not all of them. */
+ afs_warn("afs: all buffers locked\n");
+ return 0;
+ }
+
+ BufferData = (char *) afs_osi_Alloc(AFS_BUFFER_PAGESIZE * NPB);
+ for (i = 0; i< NPB; i++) {
+ /* Fill in each buffer with an empty indication. */
+ tp = &Buffers[i + nbuffers];
+ tp->fid = NULLIDX;
+ afs_reset_inode(&tp->inode);
+ tp->accesstime = 0;
+ tp->lockers = 0;
+ tp->data = &BufferData[AFS_BUFFER_PAGESIZE * i];
+ tp->hashIndex = 0;
+ tp->dirty = 0;
+ AFS_RWLOCK_INIT(&tp->lock, "buffer lock");
+ }
+ lp = &Buffers[nbuffers];
+ nbuffers += NPB;
}
if (lp->dirty) {
/* see DFlush for rationale for not getting and locking the dcache */
- tfile = afs_CFileOpen(lp->inode);
+ tfile = afs_CFileOpen(&lp->inode);
afs_CFileWrite(tfile, lp->page * AFS_BUFFER_PAGESIZE, lp->data,
AFS_BUFFER_PAGESIZE);
lp->dirty = 0;
/* Now fill in the header. */
lp->fid = adc->index;
- lp->inode = adc->f.inode;
+ afs_copy_inode(&lp->inode, &adc->f.inode);
lp->page = apage;
lp->accesstime = timecounter++;
FixupBucket(lp); /* move to the right hash bucket */
}
void
-DRelease(register struct buffer *bp, int flag)
+DRelease(void *loc, int flag)
{
/* Release a buffer, specifying whether or not the buffer has been
* modified by the locker. */
+ register struct buffer *bp = (struct buffer *)loc;
register int index;
-#if defined(AFS_USEBUFFERS)
register struct buffer *tp;
-#endif
AFS_STATCNT(DRelease);
if (!bp)
return;
-#if defined(AFS_USEBUFFERS)
/* look for buffer by scanning Unix buffers for appropriate address */
+ /* careful: despite the declaration above at this point bp is still simply
+ * an address inside the buffer, not a pointer to the buffer header */
tp = Buffers;
for (index = 0; index < nbuffers; index += NPB, tp += NPB) {
- if ((afs_int32) bp >= (afs_int32) tp->data
- && (afs_int32) bp <
- (afs_int32) tp->data + AFS_BUFFER_PAGESIZE * NPB) {
+ if ( (char *) bp >= (char *) tp->data &&
+ (char *) bp < (char *) tp->data + AFS_BUFFER_PAGESIZE * NPB) {
/* we found the right range */
- index += ((afs_int32) bp - (afs_int32) tp->data) >> LOGPS;
+ index += ((char *) bp - (char *) tp->data) >> LOGPS;
break;
}
}
-#else
- index = (((char *)bp) - ((char *)BufferData)) >> LOGPS;
-#endif
- bp = &(Buffers[index]);
- MObtainWriteLock(&bp->lock, 261);
- bp->lockers--;
+ tp = &(Buffers[index]);
+ ObtainWriteLock(&tp->lock, 261);
+ tp->lockers--;
if (flag)
- bp->dirty = 1;
- MReleaseWriteLock(&bp->lock);
+ tp->dirty = 1;
+ ReleaseWriteLock(&tp->lock);
}
int
DVOffset(register void *ap)
{
/* Return the byte within a file represented by a buffer pointer. */
- register struct buffer *bp;
register int index;
-#if defined(AFS_USEBUFFERS)
register struct buffer *tp;
-#endif
AFS_STATCNT(DVOffset);
- bp = ap;
-#if defined(AFS_USEBUFFERS)
/* look for buffer by scanning Unix buffers for appropriate address */
+ /* see comment in DRelease about the meaning of ap/bp */
tp = Buffers;
for (index = 0; index < nbuffers; index += NPB, tp += NPB) {
- if ((afs_int32) bp >= (afs_int32) tp->data
- && (afs_int32) bp <
- (afs_int32) tp->data + AFS_BUFFER_PAGESIZE * NPB) {
+ if ( (char *) ap >= (char *) tp->data &&
+ (char *) ap < (char *) tp->data + AFS_BUFFER_PAGESIZE * NPB) {
/* we found the right range */
- index += ((afs_int32) bp - (afs_int32) tp->data) >> LOGPS;
+ index += ((char *) ap - (char *) tp->data) >> LOGPS;
break;
}
}
-#else
- index = (((char *)bp) - ((char *)BufferData)) >> LOGPS;
-#endif
if (index < 0 || index >= nbuffers)
return -1;
- bp = &(Buffers[index]);
- return AFS_BUFFER_PAGESIZE * bp->page + (int)(((char *)ap) - bp->data);
+ tp = &(Buffers[index]);
+ return AFS_BUFFER_PAGESIZE * tp->page + (int)(((char *)ap) - tp->data);
}
/*!
register struct buffer *tb;
AFS_STATCNT(DZap);
- MObtainReadLock(&afs_bufferLock);
+ ObtainReadLock(&afs_bufferLock);
for (i = 0; i <= PHPAGEMASK; i++)
for (tb = phTable[pHash(adc->index, i)]; tb; tb = tb->hashNext)
if (tb->fid == adc->index) {
- MObtainWriteLock(&tb->lock, 262);
+ ObtainWriteLock(&tb->lock, 262);
tb->fid = NULLIDX;
- tb->inode = 0;
+ afs_reset_inode(&tb->inode);
tb->dirty = 0;
- MReleaseWriteLock(&tb->lock);
+ ReleaseWriteLock(&tb->lock);
+ }
+ ReleaseReadLock(&afs_bufferLock);
+}
+
+static void
+DFlushBuffer(struct buffer *ab) {
+ struct osi_file *tfile;
+
+ tfile = afs_CFileOpen(&ab->inode);
+ afs_CFileWrite(tfile, ab->page * AFS_BUFFER_PAGESIZE,
+ ab->data, AFS_BUFFER_PAGESIZE);
+ ab->dirty = 0; /* Clear the dirty flag */
+ afs_CFileClose(tfile);
+}
+
+void
+DFlushDCache(struct dcache *adc)
+{
+ int i;
+ struct buffer *tb;
+
+ ObtainReadLock(&afs_bufferLock);
+
+ for (i = 0; i <= PHPAGEMASK; i++)
+ for (tb = phTable[pHash(adc->index, i)]; tb; tb = tb->hashNext)
+ if (tb->fid == adc->index) {
+ ObtainWriteLock(&tb->lock, 701);
+ tb->lockers++;
+ ReleaseReadLock(&afs_bufferLock);
+ if (tb->dirty) {
+ DFlushBuffer(tb);
+ }
+ tb->lockers--;
+ ReleaseWriteLock(&tb->lock);
+ ObtainReadLock(&afs_bufferLock);
}
- MReleaseReadLock(&afs_bufferLock);
+
+ ReleaseReadLock(&afs_bufferLock);
}
void
/* Flush all the modified buffers. */
register int i;
register struct buffer *tb;
- struct osi_file *tfile;
AFS_STATCNT(DFlush);
tb = Buffers;
- MObtainReadLock(&afs_bufferLock);
+ ObtainReadLock(&afs_bufferLock);
for (i = 0; i < nbuffers; i++, tb++) {
if (tb->dirty) {
- MObtainWriteLock(&tb->lock, 263);
+ ObtainWriteLock(&tb->lock, 263);
tb->lockers++;
- MReleaseReadLock(&afs_bufferLock);
+ ReleaseReadLock(&afs_bufferLock);
if (tb->dirty) {
/* it seems safe to do this I/O without having the dcache
* locked, since the only things that will update the data in
* we cannot lock afs_xdcache). In addition, we cannot obtain
* a dcache lock while holding the tb->lock of the same file
* since that can deadlock with DRead/DNew */
- tfile = afs_CFileOpen(tb->inode);
- afs_CFileWrite(tfile, tb->page * AFS_BUFFER_PAGESIZE,
- tb->data, AFS_BUFFER_PAGESIZE);
- tb->dirty = 0; /* Clear the dirty flag */
- afs_CFileClose(tfile);
+ DFlushBuffer(tb);
}
tb->lockers--;
- MReleaseWriteLock(&tb->lock);
- MObtainReadLock(&afs_bufferLock);
+ ReleaseWriteLock(&tb->lock);
+ ObtainReadLock(&afs_bufferLock);
}
}
- MReleaseReadLock(&afs_bufferLock);
+ ReleaseReadLock(&afs_bufferLock);
}
void *
/* Same as read, only do *not* even try to read the page, since it probably doesn't exist. */
register struct buffer *tb;
AFS_STATCNT(DNew);
- MObtainWriteLock(&afs_bufferLock, 264);
+ ObtainWriteLock(&afs_bufferLock, 264);
if ((tb = afs_newslot(adc, page, NULL)) == 0) {
- MReleaseWriteLock(&afs_bufferLock);
+ ReleaseWriteLock(&afs_bufferLock);
return 0;
}
/* extend the chunk, if needed */
afs_AdjustSize(adc, (page + 1) * AFS_BUFFER_PAGESIZE);
afs_WriteDCache(adc, 1);
}
- MObtainWriteLock(&tb->lock, 265);
- MReleaseWriteLock(&afs_bufferLock);
+ ObtainWriteLock(&tb->lock, 265);
tb->lockers++;
- MReleaseWriteLock(&tb->lock);
+ ReleaseWriteLock(&afs_bufferLock);
+ ReleaseWriteLock(&tb->lock);
return tb->data;
}
void
shutdown_bufferpackage(void)
{
-#if defined(AFS_USEBUFFERS)
register struct buffer *tp;
-#endif
int i;
AFS_STATCNT(shutdown_bufferpackage);
DFlush();
if (afs_cold_shutdown) {
dinit_flag = 0;
-#if !defined(AFS_USEBUFFERS)
- afs_osi_Free(BufferData, nbuffers * AFS_BUFFER_PAGESIZE);
-#else
tp = Buffers;
for (i = 0; i < nbuffers; i += NPB, tp += NPB) {
+#if defined(AFS_USEBUFFERS)
/* The following check shouldn't be necessary and it will be removed soon */
if (!tp->bufp)
afs_warn
- ("shutdown_bufferpackage: bufp == 0!! Shouldn't happen\n");
+ ("afs: shutdown_bufferpackage: bufp == 0!! Shouldn't happen\n");
else {
brelse(tp->bufp);
tp->bufp = 0;
}
- }
+#else
+ afs_osi_Free(tp->data, NPB * AFS_BUFFER_PAGESIZE);
#endif
+ }
afs_osi_Free(Buffers, nbuffers * sizeof(struct buffer));
nbuffers = 0;
timecounter = 1;
for (i = 0; i < PHSIZE; i++)
phTable[i] = 0;
- memset((char *)&afs_bufferLock, 0, sizeof(afs_lock_t));
+ memset(&afs_bufferLock, 0, sizeof(afs_lock_t));
}
}
git://git.openafs.org / openafs.git / blobdiff