From bb51f7df0688f137998c3746705a346c7d8323c2 Mon Sep 17 00:00:00 2001 From: Peng Tao Date: Fri, 24 Aug 2012 00:27:51 +0800 Subject: [PATCH] pnfsblock: fix partial page buffer wirte commit fe6e1e8d9fad86873eb74a26e80a8f91f9e870b5 upstream. If applications use flock to protect its write range, generic NFS will not do read-modify-write cycle at page cache level. Therefore LD should know how to handle non-sector aligned writes. Otherwise there will be data corruption. Signed-off-by: Peng Tao Signed-off-by: Trond Myklebust --- fs/nfs/blocklayout/blocklayout.c | 176 +++++++++++++++++++++++++++++++++++--- fs/nfs/blocklayout/blocklayout.h | 1 + 2 files changed, 165 insertions(+), 12 deletions(-) diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c index 7f6a23f..d16dae2 100644 --- a/fs/nfs/blocklayout/blocklayout.c +++ b/fs/nfs/blocklayout/blocklayout.c @@ -162,25 +162,39 @@ static struct bio *bl_alloc_init_bio(int npg, sector_t isect, return bio; } -static struct bio *bl_add_page_to_bio(struct bio *bio, int npg, int rw, +static struct bio *do_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) + struct parallel_io *par, + unsigned int offset, int len) { + isect = isect + (offset >> SECTOR_SHIFT); + dprintk("%s: npg %d rw %d isect %llu offset %u len %d\n", __func__, + npg, rw, (unsigned long long)isect, offset, len); retry: if (!bio) { bio = bl_alloc_init_bio(npg, isect, be, end_io, par); if (!bio) return ERR_PTR(-ENOMEM); } - if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) { + if (bio_add_page(bio, page, len, offset) < len) { bio = bl_submit_bio(rw, bio); goto 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) { @@ -443,6 +457,107 @@ map_block(struct buffer_head *bh, sector_t isect, struct pnfs_block_extent *be) 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_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. */ @@ -476,7 +591,6 @@ init_page_for_write(struct page *page, struct pnfs_block_extent *cow_read) SetPageUptodate(page); cleanup: - bl_put_extent(cow_read); if (bh) free_buffer_head(bh); if (ret) { @@ -547,6 +661,7 @@ bl_write_pagelist(struct nfs_write_data *wdata, int sync) struct parallel_io *par; loff_t offset = wdata->args.offset; size_t count = wdata->args.count; + unsigned int pg_offset, pg_len, saved_len; struct page **pages = wdata->args.pages; struct page *page; pgoff_t index; @@ -651,10 +766,11 @@ next_page: if (!extent_length) { /* 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(wdata->lseg), - isect, NULL); + isect, &cow_read); if (!be || !is_writable(be, isect)) { wdata->pnfs_error = -EINVAL; goto out; @@ -671,7 +787,26 @@ next_page: extent_length = be->be_length - (isect - be->be_f_offset); } - if (be->be_state == PNFS_BLOCK_INVALID_DATA) { + + 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; + + 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); + wdata->pnfs_error = ret; + goto out; + } + ret = bl_mark_sectors_init(be->be_inval, isect, PAGE_CACHE_SECTORS); if (unlikely(ret)) { @@ -680,15 +815,33 @@ next_page: wdata->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 = bl_add_page_to_bio(bio, wdata->npages - i, WRITE, + bio = do_add_page_to_bio(bio, wdata->npages - i, WRITE, isect, pages[i], be, - bl_end_io_write, par); + bl_end_io_write, par, + pg_offset, pg_len); if (IS_ERR(bio)) { wdata->pnfs_error = PTR_ERR(bio); bio = NULL; goto out; } + offset += saved_len; + count -= saved_len; isect += PAGE_CACHE_SECTORS; last_isect = isect; extent_length -= PAGE_CACHE_SECTORS; @@ -706,17 +859,16 @@ next_page: } write_done: - wdata->res.count = (last_isect << SECTOR_SHIFT) - (offset); - if (count < wdata->res.count) { - wdata->res.count = count; - } + wdata->res.count = wdata->args.count; out: bl_put_extent(be); + bl_put_extent(cow_read); bl_submit_bio(WRITE, bio); put_parallel(par); return PNFS_ATTEMPTED; out_mds: bl_put_extent(be); + bl_put_extent(cow_read); kfree(par); return PNFS_NOT_ATTEMPTED; } diff --git a/fs/nfs/blocklayout/blocklayout.h b/fs/nfs/blocklayout/blocklayout.h index 0335069..39bb51a 100644 --- a/fs/nfs/blocklayout/blocklayout.h +++ b/fs/nfs/blocklayout/blocklayout.h @@ -41,6 +41,7 @@ #define PAGE_CACHE_SECTORS (PAGE_CACHE_SIZE >> SECTOR_SHIFT) #define PAGE_CACHE_SECTOR_SHIFT (PAGE_CACHE_SHIFT - SECTOR_SHIFT) +#define SECTOR_SIZE (1 << SECTOR_SHIFT) struct block_mount_id { spinlock_t bm_lock; /* protects list */ -- 1.7.9.5