From 561295a32579e2db3b22f74d1f45d5c4c4fd9375 Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Sat, 29 Sep 2018 13:51:01 +1000 Subject: [PATCH] iomap: set page dirty after partial delalloc on mkwrite The iomap page fault mechanism currently dirties the associated page after the full block range of the page has been allocated. This leaves the page susceptible to delayed allocations without ever being set dirty on sub-page block sized filesystems. For example, consider a page fault on a page with one preexisting real (non-delalloc) block allocated in the middle of the page. The first iomap_apply() iteration performs delayed allocation on the range up to the preexisting block, the next iteration finds the preexisting block, and the last iteration attempts to perform delayed allocation on the range after the prexisting block to the end of the page. If the first allocation succeeds and the final allocation fails with -ENOSPC, iomap_apply() returns the error and iomap_page_mkwrite() fails to dirty the page having already performed partial delayed allocation. This eventually results in the page being invalidated without ever converting the delayed allocation to real blocks. This problem is reliably reproduced by generic/083 on XFS on ppc64 systems (64k page size, 4k block size). It results in leaked delalloc blocks on inode reclaim, which triggers an assert failure in xfs_fs_destroy_inode() and filesystem accounting inconsistency. Move the set_page_dirty() call from iomap_page_mkwrite() to the actor callback, similar to how the buffer head implementation works. The actor callback is called iff ->iomap_begin() returns success, so ensures the page is dirtied as soon as possible after an allocation. Signed-off-by: Brian Foster Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner --- fs/iomap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/iomap.c b/fs/iomap.c index 74762b1ec233..ec15cf2ec696 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -1051,6 +1051,7 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, } else { WARN_ON_ONCE(!PageUptodate(page)); iomap_page_create(inode, page); + set_page_dirty(page); } return length; @@ -1090,7 +1091,6 @@ int iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops) length -= ret; } - set_page_dirty(page); wait_for_stable_page(page); return VM_FAULT_LOCKED; out_unlock: -- 2.30.2