Return-Path: Received: from merit-proxy01.merit.edu ([207.75.116.193]:48197 "EHLO merit-proxy01.merit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752349Ab1FNCdJ (ORCPT ); Mon, 13 Jun 2011 22:33:09 -0400 Message-Id: In-Reply-To: References: Subject: [PATCH 26/33] pnfsblock: write_begin To: Benny Halevy Cc: linux-nfs@vger.kernel.org, peter honeyman Date: Mon, 13 Jun 2011 22:33:06 -0400 From: Jim Rees Sender: linux-nfs-owner@vger.kernel.org List-ID: Content-Type: text/plain MIME-Version: 1.0 From: Fred Isaman Implements bl_write_begin and bl_do_flush, allowing block driver to read in page "around" the data that is about to be copied to the page. [pnfsblock: fix 64-bit compiler warnings for write_begin] [pnfsblock: write_begin adjust for removed fields] Signed-off-by: Fred Isaman Signed-off-by: Benny Halevy --- fs/nfs/blocklayout/blocklayout.c | 178 +++++++++++++++++++++++++++++++++++++- 1 files changed, 177 insertions(+), 1 deletions(-) diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c index d9bcb13..b9b961f 100644 --- a/fs/nfs/blocklayout/blocklayout.c +++ b/fs/nfs/blocklayout/blocklayout.c @@ -31,6 +31,8 @@ */ #include #include + +#include /* various write calls */ #include /* struct bio */ #include #include "blocklayout.h" @@ -589,11 +591,185 @@ bl_clear_layoutdriver(struct nfs_server *server) return 0; } +/* STUB - mark intersection of layout and page as bad, so is not + * used again. + */ +static void mark_bad_read(void) +{ + return; +} + +/* Copied from buffer.c */ +static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) +{ + if (uptodate) { + set_buffer_uptodate(bh); + } else { + /* This happens, due to failed READA attempts. */ + clear_buffer_uptodate(bh); + } + unlock_buffer(bh); +} + +/* Copied from buffer.c */ +static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) +{ + __end_buffer_read_notouch(bh, uptodate); +} + +/* + * map_block: map a requested I/0 block (isect) into an offset in the LVM + * meta block_device + */ +static void +map_block(sector_t isect, struct pnfs_block_extent *be, struct buffer_head *bh) +{ + 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 - 9); + + dprintk("%s isect %ld, bh->b_blocknr %ld, using bsize %Zd\n", + __func__, (long)isect, + (long)bh->b_blocknr, + bh->b_size); + return; +} + +/* Given an unmapped page, zero it (or read in page for COW), + * and set appropriate flags/markings, but it is safe to not initialize + * the range given in [from, to). + */ +/* This is loosely based on nobh_write_begin */ +static int +init_page_for_write(struct pnfs_block_layout *bl, struct page *page, + unsigned from, unsigned to, sector_t **pages_to_mark) +{ + struct buffer_head *bh; + int inval, ret = -EIO; + struct pnfs_block_extent *be = NULL, *cow_read = NULL; + sector_t isect; + + dprintk("%s enter, %p\n", __func__, page); + bh = alloc_page_buffers(page, PAGE_CACHE_SIZE, 0); + if (!bh) { + ret = -ENOMEM; + goto cleanup; + } + + isect = (sector_t)page->index << (PAGE_CACHE_SHIFT - 9); + be = find_get_extent(bl, isect, &cow_read); + if (!be) + goto cleanup; + inval = is_hole(be, isect); + dprintk("%s inval=%i, from=%u, to=%u\n", __func__, inval, from, to); + if (inval) { + if (be->be_state == PNFS_BLOCK_NONE_DATA) { + dprintk("%s PANIC - got NONE_DATA extent %p\n", + __func__, be); + goto cleanup; + } + map_block(isect, be, bh); + unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); + } + if (PageUptodate(page)) { + /* Do nothing */ + } else if (inval & !cow_read) { + zero_user_segments(page, 0, from, to, PAGE_CACHE_SIZE); + } else if (0 < from || PAGE_CACHE_SIZE > to) { + struct pnfs_block_extent *read_extent; + + read_extent = (inval && cow_read) ? cow_read : be; + map_block(isect, read_extent, bh); + lock_buffer(bh); + bh->b_end_io = end_buffer_read_nobh; + submit_bh(READ, bh); + dprintk("%s: Waiting for buffer read\n", __func__); + /* XXX Don't really want to hold layout lock here */ + wait_on_buffer(bh); + if (!buffer_uptodate(bh)) + goto cleanup; + } + if (be->be_state == PNFS_BLOCK_INVALID_DATA) { + /* There is a BUG here if is a short copy after write_begin, + * but I think this is a generic fs bug. The problem is that + * we have marked the page as initialized, but it is possible + * that the section not copied may never get copied. + */ + ret = mark_initialized_sectors(be->be_inval, isect, + PAGE_CACHE_SECTORS, + pages_to_mark); + /* Want to preallocate mem so above can't fail */ + if (ret) + goto cleanup; + } + SetPageMappedToDisk(page); + ret = 0; + +cleanup: + free_buffer_head(bh); + put_extent(be); + put_extent(cow_read); + if (ret) { + /* Need to mark layout with bad read...should now + * just use nfs4 for reads and writes. + */ + mark_bad_read(); + } + return ret; +} + static int bl_write_begin(struct pnfs_layout_segment *lseg, struct page *page, loff_t pos, unsigned count, struct pnfs_fsdata *fsdata) { - return 0; + unsigned from, to; + int ret; + sector_t *pages_to_mark = NULL; + struct pnfs_block_layout *bl = BLK_LSEG2EXT(lseg); + + dprintk("%s enter, %u@%lld\n", __func__, count, pos); + print_page(page); + /* The following code assumes blocksize >= PAGE_CACHE_SIZE */ + if (bl->bl_blocksize < (PAGE_CACHE_SIZE >> 9)) { + dprintk("%s Can't handle blocksize %llu\n", __func__, + (u64)bl->bl_blocksize); + put_lseg(fsdata->lseg); + fsdata->lseg = NULL; + return 0; + } + if (PageMappedToDisk(page)) { + /* Basically, this is a flag that says we have + * successfully called write_begin already on this page. + */ + /* NOTE - there are cache consistency issues here. + * For example, what if the layout is recalled, then regained? + * If the file is closed and reopened, will the page flags + * be reset? If not, we'll have to use layout info instead of + * the page flag. + */ + return 0; + } + from = pos & (PAGE_CACHE_SIZE - 1); + to = from + count; + ret = init_page_for_write(bl, page, from, to, &pages_to_mark); + if (ret) { + dprintk("%s init page failed with %i", __func__, ret); + /* Revert back to plain NFS and just continue on with + * write. This assumes there is no request attached, which + * should be true if we get here. + */ + BUG_ON(PagePrivate(page)); + put_lseg(fsdata->lseg); + fsdata->lseg = NULL; + kfree(pages_to_mark); + ret = 0; + } else { + fsdata->private = pages_to_mark; + } + return ret; } static int -- 1.7.4.1