Use the new PNFS_READ_WHOLE_PAGE flag to offload read-modify-write
handling to core nfs code, and remove a huge chunk of deadlock prone
mess from the block layout writeback path.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/nfs/blocklayout/blocklayout.c | 500 +++++----------------------------------
1 file changed, 64 insertions(+), 436 deletions(-)
diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 87a633d..6484b9f 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -35,7 +35,6 @@
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/bio.h> /* struct bio */
-#include <linux/buffer_head.h> /* various write calls */
#include <linux/prefetch.h>
#include <linux/pagevec.h>
@@ -188,16 +187,6 @@ retry:
return bio;
}
-static struct bio *bl_add_page_to_bio(struct bio *bio, int npg, int rw,
- sector_t isect, struct page *page,
- struct pnfs_block_extent *be,
- void (*end_io)(struct bio *, int err),
- struct parallel_io *par)
-{
- return do_add_page_to_bio(bio, npg, rw, isect, page, be,
- end_io, par, 0, PAGE_CACHE_SIZE);
-}
-
/* This is basically copied from mpage_end_io_read */
static void bl_end_io_read(struct bio *bio, int err)
{
@@ -293,8 +282,8 @@ bl_read_pagelist(struct nfs_pgio_header *hdr)
}
}
+ pg_offset = f_offset & ~PAGE_CACHE_MASK;
if (is_dio) {
- pg_offset = f_offset & ~PAGE_CACHE_MASK;
if (pg_offset + bytes_left > PAGE_CACHE_SIZE)
pg_len = PAGE_CACHE_SIZE - pg_offset;
else
@@ -305,7 +294,7 @@ bl_read_pagelist(struct nfs_pgio_header *hdr)
isect += (pg_offset >> SECTOR_SHIFT);
extent_length -= (pg_offset >> SECTOR_SHIFT);
} else {
- pg_offset = 0;
+ BUG_ON(pg_offset != 0);
pg_len = PAGE_CACHE_SIZE;
}
@@ -383,29 +372,6 @@ static void mark_extents_written(struct pnfs_block_layout *bl,
}
}
-static void bl_end_io_write_zero(struct bio *bio, int err)
-{
- struct parallel_io *par = bio->bi_private;
- struct bio_vec *bvec;
- int i;
-
- bio_for_each_segment_all(bvec, bio, i) {
- /* This is the zeroing page we added */
- end_page_writeback(bvec->bv_page);
- page_cache_release(bvec->bv_page);
- }
-
- if (unlikely(err)) {
- struct nfs_pgio_header *header = par->data;
-
- if (!header->pnfs_error)
- header->pnfs_error = -EIO;
- pnfs_set_lo_fail(header->lseg);
- }
- bio_put(bio);
- put_parallel(par);
-}
-
static void bl_end_io_write(struct bio *bio, int err)
{
struct parallel_io *par = bio->bi_private;
@@ -455,256 +421,22 @@ static void bl_end_par_io_write(void *data, int num_se)
schedule_work(&hdr->task.u.tk_work);
}
-/* FIXME STUB - mark intersection of layout and page as bad, so is not
- * used again.
- */
-static void mark_bad_read(void)
-{
- return;
-}
-
-/*
- * map_block: map a requested I/0 block (isect) into an offset in the LVM
- * block_device
- */
-static void
-map_block(struct buffer_head *bh, sector_t isect, struct pnfs_block_extent *be)
-{
- dprintk("%s enter be=%p\n", __func__, be);
-
- set_buffer_mapped(bh);
- bh->b_bdev = be->be_mdev;
- bh->b_blocknr = (isect - be->be_f_offset + be->be_v_offset) >>
- (be->be_mdev->bd_inode->i_blkbits - SECTOR_SHIFT);
-
- dprintk("%s isect %llu, bh->b_blocknr %ld, using bsize %Zd\n",
- __func__, (unsigned long long)isect, (long)bh->b_blocknr,
- bh->b_size);
- return;
-}
-
-static void
-bl_read_single_end_io(struct bio *bio, int error)
-{
- struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
- struct page *page = bvec->bv_page;
-
- /* Only one page in bvec */
- unlock_page(page);
-}
-
-static int
-bl_do_readpage_sync(struct page *page, struct pnfs_block_extent *be,
- unsigned int offset, unsigned int len)
-{
- struct bio *bio;
- struct page *shadow_page;
- sector_t isect;
- char *kaddr, *kshadow_addr;
- int ret = 0;
-
- dprintk("%s: offset %u len %u\n", __func__, offset, len);
-
- shadow_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
- if (shadow_page == NULL)
- return -ENOMEM;
-
- bio = bio_alloc(GFP_NOIO, 1);
- if (bio == NULL)
- return -ENOMEM;
-
- isect = (page->index << PAGE_CACHE_SECTOR_SHIFT) +
- (offset / SECTOR_SIZE);
-
- bio->bi_iter.bi_sector = isect - be->be_f_offset + be->be_v_offset;
- bio->bi_bdev = be->be_mdev;
- bio->bi_end_io = bl_read_single_end_io;
-
- lock_page(shadow_page);
- if (bio_add_page(bio, shadow_page,
- SECTOR_SIZE, round_down(offset, SECTOR_SIZE)) == 0) {
- unlock_page(shadow_page);
- bio_put(bio);
- return -EIO;
- }
-
- submit_bio(READ, bio);
- wait_on_page_locked(shadow_page);
- if (unlikely(!test_bit(BIO_UPTODATE, &bio->bi_flags))) {
- ret = -EIO;
- } else {
- kaddr = kmap_atomic(page);
- kshadow_addr = kmap_atomic(shadow_page);
- memcpy(kaddr + offset, kshadow_addr + offset, len);
- kunmap_atomic(kshadow_addr);
- kunmap_atomic(kaddr);
- }
- __free_page(shadow_page);
- bio_put(bio);
-
- return ret;
-}
-
-static int
-bl_read_partial_page_sync(struct page *page, struct pnfs_block_extent *be,
- unsigned int dirty_offset, unsigned int dirty_len,
- bool full_page)
-{
- int ret = 0;
- unsigned int start, end;
-
- if (full_page) {
- start = 0;
- end = PAGE_CACHE_SIZE;
- } else {
- start = round_down(dirty_offset, SECTOR_SIZE);
- end = round_up(dirty_offset + dirty_len, SECTOR_SIZE);
- }
-
- dprintk("%s: offset %u len %d\n", __func__, dirty_offset, dirty_len);
- if (!be) {
- zero_user_segments(page, start, dirty_offset,
- dirty_offset + dirty_len, end);
- if (start == 0 && end == PAGE_CACHE_SIZE &&
- trylock_page(page)) {
- SetPageUptodate(page);
- unlock_page(page);
- }
- return ret;
- }
-
- if (start != dirty_offset)
- ret = bl_do_readpage_sync(page, be, start, dirty_offset - start);
-
- if (!ret && (dirty_offset + dirty_len < end))
- ret = bl_do_readpage_sync(page, be, dirty_offset + dirty_len,
- end - dirty_offset - dirty_len);
-
- return ret;
-}
-
-/* Given an unmapped page, zero it or read in page for COW, page is locked
- * by caller.
- */
-static int
-init_page_for_write(struct page *page, struct pnfs_block_extent *cow_read)
-{
- struct buffer_head *bh = NULL;
- int ret = 0;
- sector_t isect;
-
- dprintk("%s enter, %p\n", __func__, page);
- BUG_ON(PageUptodate(page));
- if (!cow_read) {
- zero_user_segment(page, 0, PAGE_SIZE);
- SetPageUptodate(page);
- goto cleanup;
- }
-
- bh = alloc_page_buffers(page, PAGE_CACHE_SIZE, 0);
- if (!bh) {
- ret = -ENOMEM;
- goto cleanup;
- }
-
- isect = (sector_t) page->index << PAGE_CACHE_SECTOR_SHIFT;
- map_block(bh, isect, cow_read);
- if (!bh_uptodate_or_lock(bh))
- ret = bh_submit_read(bh);
- if (ret)
- goto cleanup;
- SetPageUptodate(page);
-
-cleanup:
- if (bh)
- free_buffer_head(bh);
- if (ret) {
- /* Need to mark layout with bad read...should now
- * just use nfs4 for reads and writes.
- */
- mark_bad_read();
- }
- return ret;
-}
-
-/* Find or create a zeroing page marked being writeback.
- * Return ERR_PTR on error, NULL to indicate skip this page and page itself
- * to indicate write out.
- */
-static struct page *
-bl_find_get_zeroing_page(struct inode *inode, pgoff_t index,
- struct pnfs_block_extent *cow_read)
-{
- struct page *page;
- int locked = 0;
- page = find_get_page(inode->i_mapping, index);
- if (page)
- goto check_page;
-
- page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
- if (unlikely(!page)) {
- dprintk("%s oom\n", __func__);
- return ERR_PTR(-ENOMEM);
- }
- locked = 1;
-
-check_page:
- /* PageDirty: Other will write this out
- * PageWriteback: Other is writing this out
- * PageUptodate: It was read before
- */
- if (PageDirty(page) || PageWriteback(page)) {
- print_page(page);
- if (locked)
- unlock_page(page);
- page_cache_release(page);
- return NULL;
- }
-
- if (!locked) {
- lock_page(page);
- locked = 1;
- goto check_page;
- }
- if (!PageUptodate(page)) {
- /* New page, readin or zero it */
- init_page_for_write(page, cow_read);
- }
- set_page_writeback(page);
- unlock_page(page);
-
- return page;
-}
-
static enum pnfs_try_status
bl_write_pagelist(struct nfs_pgio_header *header, int sync)
{
- int i, ret, npg_zero, pg_index, last = 0;
+ int i, ret;
struct bio *bio = NULL;
- struct pnfs_block_extent *be = NULL, *cow_read = NULL;
- sector_t isect, last_isect = 0, extent_length = 0;
+ struct pnfs_block_extent *be = NULL;
+ sector_t isect, extent_length = 0;
struct parallel_io *par = NULL;
loff_t offset = header->args.offset;
size_t count = header->args.count;
- unsigned int pg_offset, pg_len, saved_len;
struct page **pages = header->args.pages;
- struct page *page;
- pgoff_t index;
- u64 temp;
- int npg_per_block =
- NFS_SERVER(header->inode)->pnfs_blksize >> PAGE_CACHE_SHIFT;
+ int pg_index = pg_index = header->args.pgbase >> PAGE_CACHE_SHIFT;
struct blk_plug plug;
dprintk("%s enter, %Zu@%lld\n", __func__, count, offset);
- blk_start_plug(&plug);
-
- if (header->dreq != NULL &&
- (!IS_ALIGNED(offset, NFS_SERVER(header->inode)->pnfs_blksize) ||
- !IS_ALIGNED(count, NFS_SERVER(header->inode)->pnfs_blksize))) {
- dprintk("pnfsblock nonblock aligned DIO writes. Resend MDS\n");
- goto out_mds;
- }
/* At this point, header->page_aray is a (sequential) list of nfs_pages.
* We want to write each, and if there is an error set pnfs_error
* to have it redone using nfs.
@@ -715,97 +447,20 @@ bl_write_pagelist(struct nfs_pgio_header *header, int sync)
par->pnfs_callback = bl_end_par_io_write;
/* At this point, have to be more careful with error handling */
- isect = (sector_t) ((offset & (long)PAGE_CACHE_MASK) >> SECTOR_SHIFT);
- be = bl_find_get_extent(BLK_LSEG2EXT(header->lseg), isect, &cow_read);
- if (!be || !is_writable(be, isect)) {
- dprintk("%s no matching extents!\n", __func__);
- goto out_mds;
- }
-
- /* First page inside INVALID extent */
- if (be->be_state == PNFS_BLOCK_INVALID_DATA) {
- if (likely(!bl_push_one_short_extent(be->be_inval)))
- par->bse_count++;
- else
- goto out_mds;
- temp = offset >> PAGE_CACHE_SHIFT;
- npg_zero = do_div(temp, npg_per_block);
- isect = (sector_t) (((offset - npg_zero * PAGE_CACHE_SIZE) &
- (long)PAGE_CACHE_MASK) >> SECTOR_SHIFT);
- extent_length = be->be_length - (isect - be->be_f_offset);
-
-fill_invalid_ext:
- dprintk("%s need to zero %d pages\n", __func__, npg_zero);
- for (;npg_zero > 0; npg_zero--) {
- if (bl_is_sector_init(be->be_inval, isect)) {
- dprintk("isect %llu already init\n",
- (unsigned long long)isect);
- goto next_page;
- }
- /* page ref released in bl_end_io_write_zero */
- index = isect >> PAGE_CACHE_SECTOR_SHIFT;
- dprintk("%s zero %dth page: index %lu isect %llu\n",
- __func__, npg_zero, index,
- (unsigned long long)isect);
- page = bl_find_get_zeroing_page(header->inode, index,
- cow_read);
- if (unlikely(IS_ERR(page))) {
- header->pnfs_error = PTR_ERR(page);
- goto out;
- } else if (page == NULL)
- goto next_page;
-
- ret = bl_mark_sectors_init(be->be_inval, isect,
- PAGE_CACHE_SECTORS);
- if (unlikely(ret)) {
- dprintk("%s bl_mark_sectors_init fail %d\n",
- __func__, ret);
- end_page_writeback(page);
- page_cache_release(page);
- header->pnfs_error = ret;
- goto out;
- }
- if (likely(!bl_push_one_short_extent(be->be_inval)))
- par->bse_count++;
- else {
- end_page_writeback(page);
- page_cache_release(page);
- header->pnfs_error = -ENOMEM;
- goto out;
- }
- /* FIXME: This should be done in bi_end_io */
- mark_extents_written(BLK_LSEG2EXT(header->lseg),
- page->index << PAGE_CACHE_SHIFT,
- PAGE_CACHE_SIZE);
-
- bio = bl_add_page_to_bio(bio, npg_zero, WRITE,
- isect, page, be,
- bl_end_io_write_zero, par);
- if (IS_ERR(bio)) {
- header->pnfs_error = PTR_ERR(bio);
- bio = NULL;
- goto out;
- }
-next_page:
- isect += PAGE_CACHE_SECTORS;
- extent_length -= PAGE_CACHE_SECTORS;
- }
- if (last)
- goto write_done;
- }
- bio = bl_submit_bio(WRITE, bio);
+ blk_start_plug(&plug);
- /* Middle pages */
- pg_index = header->args.pgbase >> PAGE_CACHE_SHIFT;
+ /* we always write out the whole page */
+ offset = offset & (loff_t)PAGE_CACHE_MASK;
+ isect = offset >> SECTOR_SHIFT;
+
for (i = pg_index; i < header->page_array.npages; i++) {
if (extent_length <= 0) {
/* We've used up the previous extent */
bl_put_extent(be);
- bl_put_extent(cow_read);
bio = bl_submit_bio(WRITE, bio);
/* Get the next one */
be = bl_find_get_extent(BLK_LSEG2EXT(header->lseg),
- isect, &cow_read);
+ isect, NULL);
if (!be || !is_writable(be, isect)) {
header->pnfs_error = -EINVAL;
goto out;
@@ -823,25 +478,10 @@ next_page:
(isect - be->be_f_offset);
}
- dprintk("%s offset %lld count %Zu\n", __func__, offset, count);
- pg_offset = offset & ~PAGE_CACHE_MASK;
- if (pg_offset + count > PAGE_CACHE_SIZE)
- pg_len = PAGE_CACHE_SIZE - pg_offset;
- else
- pg_len = count;
+ BUG_ON(offset & ~PAGE_CACHE_MASK);
- saved_len = pg_len;
if (be->be_state == PNFS_BLOCK_INVALID_DATA &&
!bl_is_sector_init(be->be_inval, isect)) {
- ret = bl_read_partial_page_sync(pages[i], cow_read,
- pg_offset, pg_len, true);
- if (ret) {
- dprintk("%s bl_read_partial_page_sync fail %d\n",
- __func__, ret);
- header->pnfs_error = ret;
- goto out;
- }
-
ret = bl_mark_sectors_init(be->be_inval, isect,
PAGE_CACHE_SECTORS);
if (unlikely(ret)) {
@@ -850,66 +490,31 @@ next_page:
header->pnfs_error = ret;
goto out;
}
-
- /* Expand to full page write */
- pg_offset = 0;
- pg_len = PAGE_CACHE_SIZE;
- } else if ((pg_offset & (SECTOR_SIZE - 1)) ||
- (pg_len & (SECTOR_SIZE - 1))){
- /* ahh, nasty case. We have to do sync full sector
- * read-modify-write cycles.
- */
- unsigned int saved_offset = pg_offset;
- ret = bl_read_partial_page_sync(pages[i], be, pg_offset,
- pg_len, false);
- pg_offset = round_down(pg_offset, SECTOR_SIZE);
- pg_len = round_up(saved_offset + pg_len, SECTOR_SIZE)
- - pg_offset;
}
-
bio = do_add_page_to_bio(bio, header->page_array.npages - i,
- WRITE,
- isect, pages[i], be,
+ WRITE, isect, pages[i], be,
bl_end_io_write, par,
- pg_offset, pg_len);
+ 0, PAGE_CACHE_SIZE);
if (IS_ERR(bio)) {
header->pnfs_error = PTR_ERR(bio);
bio = NULL;
goto out;
}
- offset += saved_len;
- count -= saved_len;
+ offset += PAGE_CACHE_SIZE;
+ count -= PAGE_CACHE_SIZE;
isect += PAGE_CACHE_SECTORS;
- last_isect = isect;
extent_length -= PAGE_CACHE_SECTORS;
}
- /* Last page inside INVALID extent */
- if (be->be_state == PNFS_BLOCK_INVALID_DATA) {
- bio = bl_submit_bio(WRITE, bio);
- temp = last_isect >> PAGE_CACHE_SECTOR_SHIFT;
- npg_zero = npg_per_block - do_div(temp, npg_per_block);
- if (npg_zero < npg_per_block) {
- last = 1;
- goto fill_invalid_ext;
- }
- }
-
-write_done:
header->res.count = header->args.count;
out:
bl_put_extent(be);
- bl_put_extent(cow_read);
bl_submit_bio(WRITE, bio);
blk_finish_plug(&plug);
put_parallel(par);
return PNFS_ATTEMPTED;
out_mds:
- blk_finish_plug(&plug);
- bl_put_extent(be);
- bl_put_extent(cow_read);
- kfree(par);
return PNFS_NOT_ATTEMPTED;
}
@@ -1188,20 +793,45 @@ bl_clear_layoutdriver(struct nfs_server *server)
}
static bool
-is_aligned_req(struct nfs_page *req, unsigned int alignment)
+is_aligned_req(struct nfs_pageio_descriptor *pgio,
+ struct nfs_page *req, unsigned int alignment)
{
- return IS_ALIGNED(req->wb_offset, alignment) &&
- IS_ALIGNED(req->wb_bytes, alignment);
+ /*
+ * Always accept buffered writes, higher layers take care of the
+ * right alignment.
+ */
+ if (pgio->pg_dreq == NULL)
+ return true;
+
+ if (!IS_ALIGNED(req->wb_offset, alignment))
+ return false;
+
+ if (IS_ALIGNED(req->wb_bytes, alignment))
+ return true;
+
+ if (req_offset(req) + req->wb_bytes == i_size_read(pgio->pg_inode)) {
+ /*
+ * If the write goes up to the inode size, just write
+ * the full page. Data past the inode size is
+ * guaranteed to be zeroed by the higher level client
+ * code, and this behaviour is mandated by RFC 5663
+ * section 2.3.2.
+ */
+ return true;
+ }
+
+ return false;
}
static void
bl_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
{
- if (pgio->pg_dreq != NULL &&
- !is_aligned_req(req, SECTOR_SIZE))
+ if (!is_aligned_req(pgio, req, SECTOR_SIZE)) {
nfs_pageio_reset_read_mds(pgio);
- else
- pnfs_generic_pg_init_read(pgio, req);
+ return;
+ }
+
+ pnfs_generic_pg_init_read(pgio, req);
}
/*
@@ -1212,10 +842,8 @@ static size_t
bl_pg_test_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
struct nfs_page *req)
{
- if (pgio->pg_dreq != NULL &&
- !is_aligned_req(req, SECTOR_SIZE))
+ if (!is_aligned_req(pgio, req, SECTOR_SIZE))
return 0;
-
return pnfs_generic_pg_test(pgio, prev, req);
}
@@ -1245,19 +873,20 @@ static u64 pnfs_num_cont_bytes(struct inode *inode, pgoff_t idx)
static void
bl_pg_init_write(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
{
- if (pgio->pg_dreq != NULL &&
- !is_aligned_req(req, PAGE_CACHE_SIZE)) {
+ u64 wb_size;
+
+ if (!is_aligned_req(pgio, req, PAGE_SIZE)) {
nfs_pageio_reset_write_mds(pgio);
- } else {
- u64 wb_size;
- if (pgio->pg_dreq == NULL)
- wb_size = pnfs_num_cont_bytes(pgio->pg_inode,
- req->wb_index);
- else
- wb_size = nfs_dreq_bytes_left(pgio->pg_dreq);
-
- pnfs_generic_pg_init_write(pgio, req, wb_size);
+ return;
}
+
+ if (pgio->pg_dreq == NULL)
+ wb_size = pnfs_num_cont_bytes(pgio->pg_inode,
+ req->wb_index);
+ else
+ wb_size = nfs_dreq_bytes_left(pgio->pg_dreq);
+
+ pnfs_generic_pg_init_write(pgio, req, wb_size);
}
/*
@@ -1268,10 +897,8 @@ static size_t
bl_pg_test_write(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
struct nfs_page *req)
{
- if (pgio->pg_dreq != NULL &&
- !is_aligned_req(req, PAGE_CACHE_SIZE))
+ if (!is_aligned_req(pgio, req, PAGE_SIZE))
return 0;
-
return pnfs_generic_pg_test(pgio, prev, req);
}
@@ -1291,6 +918,7 @@ static struct pnfs_layoutdriver_type blocklayout_type = {
.id = LAYOUT_BLOCK_VOLUME,
.name = "LAYOUT_BLOCK_VOLUME",
.owner = THIS_MODULE,
+ .flags = PNFS_READ_WHOLE_PAGE,
.read_pagelist = bl_read_pagelist,
.write_pagelist = bl_write_pagelist,
.alloc_layout_hdr = bl_alloc_layout_hdr,
--
1.9.1
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
