On Wed, Aug 8, 2012 at 9:54 AM, Peng Tao <bergwolf@xxxxxxxxx> wrote:
> 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.
>
> Cc: stable <stable@xxxxxxxxxxxxxxx>
~~~typo here... should be.
Cc: stable <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Peng Tao <tao.peng@xxxxxxx>
> ---
> fs/nfs/blocklayout/blocklayout.c | 177 +++++++++++++++++++++++++++++++++++---
> fs/nfs/blocklayout/blocklayout.h | 1 +
> 2 files changed, 166 insertions(+), 12 deletions(-)
>
> diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
> index 7ae8a60..39fa002 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)
> {
> @@ -450,6 +464,106 @@ 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.
> */
> @@ -483,7 +597,6 @@ 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) {
> @@ -555,6 +668,7 @@ 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;
> @@ -659,10 +773,11 @@ 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(header->lseg),
> - isect, NULL);
> + isect, &cow_read);
> if (!be || !is_writable(be, isect)) {
> header->pnfs_error = -EINVAL;
> goto out;
> @@ -679,7 +794,26 @@ 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);
> + header->pnfs_error = ret;
> + goto out;
> + }
> +
> ret = bl_mark_sectors_init(be->be_inval, isect,
> PAGE_CACHE_SECTORS);
> if (unlikely(ret)) {
> @@ -688,15 +822,35 @@ 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 = bl_add_page_to_bio(bio, wdata->pages.npages - i, WRITE,
> +
> +
> + bio = do_add_page_to_bio(bio, wdata->pages.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)) {
> header->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;
> @@ -714,17 +868,16 @@ 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 */
> --
> 1.7.1.262.g5ef3d
>
--
Thanks,
Tao
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