Syntax cleanup and documentation, no operational changes.
MFC after: 1 day
This commit is contained in:
parent
08b00f49c3
commit
57601bcb5d
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=85272
@ -353,6 +353,12 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
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if (bp == 0)
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return tbp;
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/*
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* We are synthesizing a buffer out of vm_page_t's, but
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* if the block size is not page aligned then the starting
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* address may not be either. Inherit the b_data offset
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* from the original buffer.
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*/
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bp->b_data = (char *)((vm_offset_t)bp->b_data |
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((vm_offset_t)tbp->b_data & PAGE_MASK));
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bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
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@ -374,17 +380,24 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
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for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
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if (i != 0) {
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if ((bp->b_npages * PAGE_SIZE) +
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round_page(size) > vp->v_mount->mnt_iosize_max)
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round_page(size) > vp->v_mount->mnt_iosize_max) {
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break;
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}
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/*
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* Shortcut some checks and try to avoid buffers that
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* would block in the lock. The same checks have to
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* be made again after we officially get the buffer.
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*/
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if ((tbp = incore(vp, lbn + i)) != NULL) {
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if (BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT))
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break;
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BUF_UNLOCK(tbp);
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for (j = 0; j < tbp->b_npages; j++)
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for (j = 0; j < tbp->b_npages; j++) {
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if (tbp->b_pages[j]->valid)
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break;
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}
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if (j != tbp->b_npages)
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break;
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@ -396,10 +409,11 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
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tbp = getblk(vp, lbn + i, size, 0, 0);
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/*
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* If the buffer is already fully valid or locked
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* (which could also mean that a background write is
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* in progress), or the buffer is not backed by VMIO,
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* stop.
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* Stop scanning if the buffer is fully valid
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* (marked B_CACHE), or locked (may be doing a
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* background write), or if the buffer is not
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* VMIO backed. The clustering code can only deal
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* with VMIO-backed buffers.
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*/
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if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
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(tbp->b_flags & B_VMIO) == 0) {
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@ -407,18 +421,33 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
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break;
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}
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/*
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* The buffer must be completely invalid in order to
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* take part in the cluster. If it is partially valid
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* then we stop.
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*/
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for (j = 0;j < tbp->b_npages; j++) {
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if (tbp->b_pages[j]->valid)
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break;
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}
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if (j != tbp->b_npages) {
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bqrelse(tbp);
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break;
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}
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/*
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* Set a read-ahead mark as appropriate
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*/
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if ((fbp && (i == 1)) || (i == (run - 1)))
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tbp->b_flags |= B_RAM;
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/*
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* Set the buffer up for an async read (XXX should
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* we do this only if we do not wind up brelse()ing?).
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* Set the block number if it isn't set, otherwise
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* if it is make sure it matches the block number we
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* expect.
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*/
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tbp->b_flags |= B_ASYNC;
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tbp->b_iocmd = BIO_READ;
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if (tbp->b_blkno == tbp->b_lblkno) {
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@ -452,10 +481,15 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
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bp->b_bufsize += tbp->b_bufsize;
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}
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for(j=0;j<bp->b_npages;j++) {
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/*
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* Fully valid pages in the cluster are already good and do not need
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* to be re-read from disk. Replace the page with bogus_page
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*/
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for (j = 0; j < bp->b_npages; j++) {
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if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) ==
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VM_PAGE_BITS_ALL)
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VM_PAGE_BITS_ALL) {
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bp->b_pages[j] = bogus_page;
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}
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}
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if (bp->b_bufsize > bp->b_kvasize)
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panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
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@ -780,6 +814,13 @@ cluster_wbuild(vp, size, start_lbn, len)
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bp->b_blkno = tbp->b_blkno;
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bp->b_lblkno = tbp->b_lblkno;
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bp->b_offset = tbp->b_offset;
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/*
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* We are synthesizing a buffer out of vm_page_t's, but
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* if the block size is not page aligned then the starting
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* address may not be either. Inherit the b_data offset
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* from the original buffer.
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*/
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bp->b_data = (char *)((vm_offset_t)bp->b_data |
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((vm_offset_t)tbp->b_data & PAGE_MASK));
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bp->b_flags |= B_CLUSTER |
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@ -849,7 +890,11 @@ cluster_wbuild(vp, size, start_lbn, len)
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buf_start(tbp);
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/*
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* If the IO is via the VM then we do some
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* special VM hackery. (yuck)
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* special VM hackery (yuck). Since the buffer's
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* block size may not be page-aligned it is possible
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* for a page to be shared between two buffers. We
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* have to get rid of the duplication when building
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* the cluster.
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*/
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if (tbp->b_flags & B_VMIO) {
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vm_page_t m;
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@ -294,8 +294,8 @@ vm_pageout_clean(m)
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vm_page_test_dirty(p);
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if ((p->dirty & p->valid) == 0 ||
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p->queue != PQ_INACTIVE ||
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p->wire_count != 0 ||
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p->hold_count != 0) {
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p->wire_count != 0 || /* may be held by buf cache */
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p->hold_count != 0) { /* may be undergoing I/O */
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ib = 0;
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break;
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}
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@ -323,8 +323,8 @@ vm_pageout_clean(m)
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vm_page_test_dirty(p);
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if ((p->dirty & p->valid) == 0 ||
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p->queue != PQ_INACTIVE ||
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p->wire_count != 0 ||
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p->hold_count != 0) {
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p->wire_count != 0 || /* may be held by buf cache */
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p->hold_count != 0) { /* may be undergoing I/O */
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break;
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}
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mc[page_base + pageout_count] = p;
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@ -714,6 +714,9 @@ vm_pageout_scan(int pass)
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if (m->flags & PG_MARKER)
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continue;
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/*
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* A held page may be undergoing I/O, so skip it.
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*/
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if (m->hold_count) {
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vm_pageq_requeue(m);
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addl_page_shortage++;
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@ -904,7 +907,8 @@ vm_pageout_scan(int pass)
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}
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/*
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* If the page has become held, then skip it
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* If the page has become held it might
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* be undergoing I/O, so skip it
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*/
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if (m->hold_count) {
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vm_pageq_requeue(m);
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