From 84ba3c2cf3156cef7aee4b2b295c84769168c226 Mon Sep 17 00:00:00 2001 From: "Yan, Zheng" Date: Thu, 18 Jun 2015 03:10:58 +0800 Subject: [PATCH] ceph: fix ceph_writepages_start() Before a page get locked, someone else can write data to the page and increase the i_size. So we should re-check the i_size after pages are locked. Signed-off-by: Yan, Zheng --- fs/ceph/addr.c | 37 +++++++++++++++++++++++-------------- 1 file changed, 23 insertions(+), 14 deletions(-) diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index 9710203..890c509 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -440,7 +440,7 @@ out: * only snap context we are allowed to write back. */ static struct ceph_snap_context *get_oldest_context(struct inode *inode, - u64 *snap_size) + loff_t *snap_size) { struct ceph_inode_info *ci = ceph_inode(inode); struct ceph_snap_context *snapc = NULL; @@ -480,8 +480,9 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) struct ceph_osd_client *osdc; struct ceph_snap_context *snapc, *oldest; loff_t page_off = page_offset(page); + loff_t snap_size = -1; long writeback_stat; - u64 truncate_size, snap_size = 0; + u64 truncate_size; u32 truncate_seq; int err = 0, len = PAGE_CACHE_SIZE; @@ -516,7 +517,7 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) spin_lock(&ci->i_ceph_lock); truncate_seq = ci->i_truncate_seq; truncate_size = ci->i_truncate_size; - if (!snap_size) + if (snap_size == -1) snap_size = i_size_read(inode); spin_unlock(&ci->i_ceph_lock); @@ -699,7 +700,8 @@ static int ceph_writepages_start(struct address_space *mapping, unsigned wsize = 1 << inode->i_blkbits; struct ceph_osd_request *req = NULL; int do_sync = 0; - u64 truncate_size, snap_size; + loff_t snap_size, i_size; + u64 truncate_size; u32 truncate_seq; /* @@ -745,7 +747,7 @@ static int ceph_writepages_start(struct address_space *mapping, retry: /* find oldest snap context with dirty data */ ceph_put_snap_context(snapc); - snap_size = 0; + snap_size = -1; snapc = get_oldest_context(inode, &snap_size); if (!snapc) { /* hmm, why does writepages get called when there @@ -753,16 +755,13 @@ retry: dout(" no snap context with dirty data?\n"); goto out; } - if (snap_size == 0) - 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); + i_size = i_size_read(inode); spin_unlock(&ci->i_ceph_lock); if (last_snapc && snapc != last_snapc) { @@ -832,8 +831,10 @@ get_more_pages: dout("waiting on writeback %p\n", page); wait_on_page_writeback(page); } - if (page_offset(page) >= snap_size) { - dout("%p page eof %llu\n", page, snap_size); + if (page_offset(page) >= + (snap_size == -1 ? i_size : snap_size)) { + dout("%p page eof %llu\n", page, + (snap_size == -1 ? i_size : snap_size)); done = 1; unlock_page(page); break; @@ -949,10 +950,18 @@ get_more_pages: } /* Format the osd request message and submit the write */ - offset = page_offset(pages[0]); - len = min(snap_size - offset, - (u64)locked_pages << PAGE_CACHE_SHIFT); + len = (u64)locked_pages << PAGE_CACHE_SHIFT; + if (snap_size == -1) { + len = min(len, (u64)i_size_read(inode) - offset); + /* writepages_finish() clears writeback pages + * according to the data length, so make sure + * data length covers all locked pages */ + len = max(len, 1 + + ((u64)(locked_pages - 1) << PAGE_CACHE_SHIFT)); + } else { + len = min(len, snap_size - offset); + } dout("writepages got %d pages at %llu~%llu\n", locked_pages, offset, len); -- 1.9.3