d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Add INVARIANTS checking that numfreebufs values are sane. Also add a

Browse Source 
per-buf flag to catch if a buf is double-counted in the free count.
This code was useful to debug an instance where a local patch at Isilon
was incorrectly managing numfreebufs for a new buf state.

Reviewed by:	jeff
Approved by:	zml (mentor)
This commit is contained in:
Matthew D Fleming 2010-06-11 17:03:26 +00:00
parent 3ba5db25bb
commit d19511c357
2 changed files with 54 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
sys/kern/vfs_bio.c
View File

@ -393,10 +393,16 @@ runningbufwakeup(struct buf *bp)
*/
static __inline void
bufcountwakeup(void)
bufcountwakeup(struct buf *bp)
{
int old;
atomic_add_int(&numfreebuffers, 1);
KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
("buf %p already counted as free", bp));
bp->b_vflags |= BV_INFREECNT;
old = atomic_fetchadd_int(&numfreebuffers, 1);
KASSERT(old >= 0 && old < nbuf,
("numfreebuffers climbed to %d", old + 1));
mtx_lock(&nblock);
if (needsbuffer) {
needsbuffer &= ~VFS_BIO_NEED_ANY;
@ -592,7 +598,7 @@ bufinit(void)
bp->b_rcred = NOCRED;
bp->b_wcred = NOCRED;
bp->b_qindex = QUEUE_EMPTY;
bp->b_vflags = 0;
bp->b_vflags = BV_INFREECNT; /* buf is counted as free */
bp->b_xflags = 0;
LIST_INIT(&bp->b_dep);
BUF_LOCKINIT(bp);
@ -686,6 +692,7 @@ bfreekva(struct buf *bp)
void
bremfree(struct buf *bp)
{
int old;
CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
KASSERT((bp->b_flags & B_REMFREE) == 0,
@ -696,8 +703,13 @@ bremfree(struct buf *bp)
bp->b_flags |= B_REMFREE;
/* Fixup numfreebuffers count. */
if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
atomic_subtract_int(&numfreebuffers, 1);
if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
("buf %p not counted in numfreebuffers", bp));
bp->b_vflags &= ~BV_INFREECNT;
old = atomic_fetchadd_int(&numfreebuffers, -1);
KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
}
}
/*
@ -723,6 +735,8 @@ bremfreef(struct buf *bp)
static void
bremfreel(struct buf *bp)
{
int old;
CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
KASSERT(bp->b_qindex != QUEUE_NONE,
@ -745,8 +759,13 @@ bremfreel(struct buf *bp)
* delayed-write, the buffer was free and we must decrement
* numfreebuffers.
*/
if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
atomic_subtract_int(&numfreebuffers, 1);
if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
KASSERT((bp->b_vflags & BV_INFREECNT) != 0,
("buf %p not counted in numfreebuffers", bp));
bp->b_vflags &= ~BV_INFREECNT;
old = atomic_fetchadd_int(&numfreebuffers, -1);
KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
}
}
@ -1448,7 +1467,7 @@ brelse(struct buf *bp)
*/
if (!(bp->b_flags & B_DELWRI))
bufcountwakeup();
bufcountwakeup(bp);
/*
* Something we can maybe free or reuse
@ -1537,7 +1556,7 @@ bqrelse(struct buf *bp)
mtx_unlock(&bqlock);
if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
bufcountwakeup();
bufcountwakeup(bp);
/*
* Something we can maybe free or reuse.
@ -1916,6 +1935,8 @@ getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
bp->b_flags = 0;
bp->b_ioflags = 0;
bp->b_xflags = 0;
KASSERT((bp->b_vflags & BV_INFREECNT) == 0,
("buf %p still counted as free?", bp));
bp->b_vflags = 0;
bp->b_vp = NULL;
bp->b_blkno = bp->b_lblkno = 0;
@ -4103,4 +4124,27 @@ DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
db_printf("\n");
}
}
DB_COMMAND(countfreebufs, db_coundfreebufs)
{
struct buf *bp;
int i, used = 0, nfree = 0;
if (have_addr) {
db_printf("usage: countfreebufs\n");
return;
}
for (i = 0; i < nbuf; i++) {
bp = &buf[i];
if ((bp->b_vflags & BV_INFREECNT) != 0)
nfree++;
else
used++;
}
db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
nfree + used);
db_printf("numfreebuffers is %d\n", numfreebuffers);
}
#endif /* DDB */

1
sys/sys/buf.h
View File

@ -247,6 +247,7 @@ struct buf {
#define BV_SCANNED 0x00000001 /* VOP_FSYNC funcs mark written bufs */
#define BV_BKGRDINPROG 0x00000002 /* Background write in progress */
#define BV_BKGRDWAIT 0x00000004 /* Background write waiting */
#define BV_INFREECNT 0x80000000 /* buf is counted in numfreebufs */
#ifdef _KERNEL
/*