From fc2744aa12da7182509b1059aa3ab53754d0c83a Mon Sep 17 00:00:00 2001 From: "Yan, Zheng" Date: Fri, 31 May 2013 16:48:29 +0800 Subject: [PATCH] ceph: fix race between page writeback and truncate The client can receive truncate request from MDS at any time. So the page writeback code need to get i_size, truncate_seq and truncate_size atomically Signed-off-by: Yan, Zheng Reviewed-by: Sage Weil --- fs/ceph/addr.c | 84 ++++++++++++++++++++++++++++------------------------------ 1 file changed, 40 insertions(+), 44 deletions(-) diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index 3e68ac1..3500b74 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -438,13 +438,12 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) struct ceph_inode_info *ci; struct ceph_fs_client *fsc; struct ceph_osd_client *osdc; - loff_t page_off = page_offset(page); - int len = PAGE_CACHE_SIZE; - loff_t i_size; - int err = 0; struct ceph_snap_context *snapc, *oldest; - u64 snap_size = 0; + loff_t page_off = page_offset(page); long writeback_stat; + u64 truncate_size, snap_size = 0; + u32 truncate_seq; + int err = 0, len = PAGE_CACHE_SIZE; dout("writepage %p idx %lu\n", page, page->index); @@ -474,13 +473,20 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) } ceph_put_snap_context(oldest); + spin_lock(&ci->i_ceph_lock); + truncate_seq = ci->i_truncate_seq; + truncate_size = ci->i_truncate_size; + if (!snap_size) + snap_size = i_size_read(inode); + spin_unlock(&ci->i_ceph_lock); + /* is this a partial page at end of file? */ - if (snap_size) - i_size = snap_size; - else - i_size = i_size_read(inode); - if (i_size < page_off + len) - len = i_size - page_off; + if (page_off >= snap_size) { + dout("%p page eof %llu\n", page, snap_size); + goto out; + } + if (snap_size < page_off + len) + len = snap_size - page_off; dout("writepage %p page %p index %lu on %llu~%u snapc %p\n", inode, page, page->index, page_off, len, snapc); @@ -494,7 +500,7 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) err = ceph_osdc_writepages(osdc, ceph_vino(inode), &ci->i_layout, snapc, page_off, len, - ci->i_truncate_seq, ci->i_truncate_size, + truncate_seq, truncate_size, &inode->i_mtime, &page, 1); if (err < 0) { dout("writepage setting page/mapping error %d %p\n", err, page); @@ -631,25 +637,6 @@ static void writepages_finish(struct ceph_osd_request *req, ceph_osdc_put_request(req); } -static struct ceph_osd_request * -ceph_writepages_osd_request(struct inode *inode, u64 offset, u64 *len, - struct ceph_snap_context *snapc, int num_ops) -{ - struct ceph_fs_client *fsc; - struct ceph_inode_info *ci; - struct ceph_vino vino; - - fsc = ceph_inode_to_client(inode); - ci = ceph_inode(inode); - vino = ceph_vino(inode); - /* BUG_ON(vino.snap != CEPH_NOSNAP); */ - - return ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout, - vino, offset, len, num_ops, CEPH_OSD_OP_WRITE, - CEPH_OSD_FLAG_WRITE|CEPH_OSD_FLAG_ONDISK, - snapc, ci->i_truncate_seq, ci->i_truncate_size, true); -} - /* * initiate async writeback */ @@ -658,7 +645,8 @@ static int ceph_writepages_start(struct address_space *mapping, { struct inode *inode = mapping->host; struct ceph_inode_info *ci = ceph_inode(inode); - struct ceph_fs_client *fsc; + struct ceph_fs_client *fsc = ceph_inode_to_client(inode); + struct ceph_vino vino = ceph_vino(inode); pgoff_t index, start, end; int range_whole = 0; int should_loop = 1; @@ -670,7 +658,8 @@ static int ceph_writepages_start(struct address_space *mapping, unsigned wsize = 1 << inode->i_blkbits; struct ceph_osd_request *req = NULL; int do_sync; - u64 snap_size; + u64 truncate_size, snap_size; + u32 truncate_seq; /* * Include a 'sync' in the OSD request if this is a data @@ -685,7 +674,6 @@ static int ceph_writepages_start(struct address_space *mapping, wbc->sync_mode == WB_SYNC_NONE ? "NONE" : (wbc->sync_mode == WB_SYNC_ALL ? "ALL" : "HOLD")); - fsc = ceph_inode_to_client(inode); if (fsc->mount_state == CEPH_MOUNT_SHUTDOWN) { pr_warning("writepage_start %p on forced umount\n", inode); return -EIO; /* we're in a forced umount, don't write! */ @@ -728,6 +716,14 @@ retry: snap_size = i_size_read(inode); dout(" oldest snapc is %p seq %lld (%d snaps)\n", snapc, snapc->seq, snapc->num_snaps); + + spin_lock(&ci->i_ceph_lock); + truncate_seq = ci->i_truncate_seq; + truncate_size = ci->i_truncate_size; + if (!snap_size) + snap_size = i_size_read(inode); + spin_unlock(&ci->i_ceph_lock); + if (last_snapc && snapc != last_snapc) { /* if we switched to a newer snapc, restart our scan at the * start of the original file range. */ @@ -739,7 +735,6 @@ retry: while (!done && index <= end) { int num_ops = do_sync ? 2 : 1; - struct ceph_vino vino; unsigned i; int first; pgoff_t next; @@ -833,17 +828,18 @@ get_more_pages: * that it will use. */ if (locked_pages == 0) { - size_t size; - BUG_ON(pages); - /* prepare async write request */ offset = (u64)page_offset(page); len = wsize; - req = ceph_writepages_osd_request(inode, - offset, &len, snapc, - num_ops); - + req = ceph_osdc_new_request(&fsc->client->osdc, + &ci->i_layout, vino, + offset, &len, num_ops, + CEPH_OSD_OP_WRITE, + CEPH_OSD_FLAG_WRITE | + CEPH_OSD_FLAG_ONDISK, + snapc, truncate_seq, + truncate_size, true); if (IS_ERR(req)) { rc = PTR_ERR(req); unlock_page(page); @@ -854,8 +850,8 @@ get_more_pages: req->r_inode = inode; max_pages = calc_pages_for(0, (u64)len); - size = max_pages * sizeof (*pages); - pages = kmalloc(size, GFP_NOFS); + pages = kmalloc(max_pages * sizeof (*pages), + GFP_NOFS); if (!pages) { pool = fsc->wb_pagevec_pool; pages = mempool_alloc(pool, GFP_NOFS); -- 2.7.4