commit a1b7a4dea6166cf46be895bce4aac67ea5160fe8 upstream. There is a race window between write_cache_pages calling clear_page_dirty_for_io and XFS calling set_page_writeback, in which the mapping for an inode is tagged neither as dirty, nor as writeback. If the COW shrinker hits in exactly that window we'll remove the delayed COW extents and writepages trying to write it back, which in release kernels will manifest as corruption of the bmap btree, and in debug kernels will trip the ASSERT about now calling xfs_bmapi_write with the COWFORK flag for holes. A complex customer load manages to hit this window fairly reliably, probably by always having COW writeback in flight while the cow shrinker runs. This patch adds another check for having the I_DIRTY_PAGES flag set, which is still set during this race window. While this fixes the problem I'm still not overly happy about the way the COW shrinker works as it still seems a bit fragile. Signed-off-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> --- fs/xfs/xfs_icache.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index 9c3e5c6..29cc988 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -1599,7 +1599,8 @@ xfs_inode_free_cowblocks( * If the mapping is dirty or under writeback we cannot touch the * CoW fork. Leave it alone if we're in the midst of a directio. */ - if (mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_DIRTY) || + if ((VFS_I(ip)->i_state & I_DIRTY_PAGES) || + mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_DIRTY) || mapping_tagged(VFS_I(ip)->i_mapping, PAGECACHE_TAG_WRITEBACK) || atomic_read(&VFS_I(ip)->i_dio_count)) return 0; -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
