From: Jeff Layton Subject: [PATCH v4 00/27] fs: introduce new writeback error reporting and convert existing API as a wrapper around it Date: Tue, 9 May 2017 11:49:03 -0400 Message-ID: <20170509154930.29524-1-jlayton@redhat.com> Cc: dhowells@redhat.com, akpm@linux-foundation.org, hch@infradead.org, ross.zwisler@linux.intel.com, mawilcox@microsoft.com, jack@suse.com, viro@zeniv.linux.org.uk, corbet@lwn.net, neilb@suse.de, clm@fb.com, tytso@mit.edu, axboe@kernel.dk, josef@toxicpanda.com, hubcap@omnibond.com, rpeterso@redhat.com, bo.li.liu@oracle.com To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, jfs-discussion@lists.sourceforge.net, linux-xfs@vger.kernel.org, cluster-devel@redhat.com, linux-f2fs-devel@lists.sourceforge.net, v9fs-developer@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-block@vger.kernel.org Return-path: Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org v4: several more cleanup patches documentation and kerneldoc comment updates fix bugs in gfs2 patches make sync_file_range use same error reporting semantics bugfixes in buffer.c convert nfs to new scheme (maybe bogus, can be dropped) v3: wb_err_t -> errseq_t conversion clean up places that re-set errors after calling filemap_* functions v2: introduce wb_err_t, use atomics Apologies for the wide posting here, but this touches a lot of areas. This is v3 of the patchset to improve how we're tracking and reporting errors that occur during pagecache writeback. There are several situations where the kernel can "lose" errors that occur during writeback, such that fsync will return success even though it failed to write back some data previously. The basic idea here is to have the kernel be more deliberate about the point from which errors are checked to ensure that that doesn't happen. Additionally, this set changes the behavior of fsync in Linux to report writeback errors on all fds instead of just the first one. This allows writers to reliably tell whether their data made it to the backing device without having to coordinate fsync calls with other writers. This set sprawls over a large swath of kernel code. I think the first 12 patches in the series are pretty straightforward and are more or less ready for merge. The real changes start with patch 13. That adds support for errseq_t, builds a new writeback error tracking API on top of that, and converts the existing code to use it. After that, there are a few cleanup patches to eliminate some unneeded error re-setting, etc. Finally, there are several patches that attempt to codify the semantics in the documentation and make it clear what filesystems should do when there are writeback errors. Unfortunately, testing this across so many filesystems is rather difficult. I have a xfstest for block-based filesystems that uses dm_error that I'll repost soon. It works well with xfs and ext4 and those now pass after this patchset. btrfs still fails however, so it may need some more work to get this right. I also don't have a good general method for testing this on network filesystems (yet!). I'd like to see better testing here and am open to suggestions. I will note that the POSIX fsync spec says this: "It is reasonable to assert that the key aspects of fsync() are unreasonable to test in a test suite. That does not make the function any less valuable, just more difficult to test. [...] It would also not be unreasonable to omit testing for fsync(), allowing it to be treated as a quality-of-implementation issue." Of course, they're talking about a POSIX conformance test, but I think the same point applies here. At this point, I'd like to start getting some of the preliminary patches merged (the first 12 or so). Most of those aren't terribly controversial and seem like reasonable bugfixes and cleanups. If any subsystem maintainers want to pick those up, then please do. After that, I'd like to get the larger changes into linux-next with an aim for merge in v4.13 or v4.14 (depending on how testing goes). Feedback is of course welcome. Jeff Layton (27): fs: remove unneeded forward definition of mm_struct from fs.h mm: drop "wait" parameter from write_one_page mm: fix mapping_set_error call in me_pagecache_dirty buffer: use mapping_set_error instead of setting the flag btrfs: btrfs_wait_tree_block_writeback can be void return fs: check for writeback errors after syncing out buffers in generic_file_fsync orangefs: don't call filemap_write_and_wait from fsync dax: set errors in mapping when writeback fails nilfs2: set the mapping error when calling SetPageError on writeback 9p: set mapping error when writeback fails in launder_page fuse: set mapping error in writepage_locked when it fails cifs: set mapping error when page writeback fails in writepage or launder_pages lib: add errseq_t type and infrastructure for handling it fs: new infrastructure for writeback error handling and reporting fs: retrofit old error reporting API onto new infrastructure fs: adapt sync_file_range to new reporting infrastructure mm: remove AS_EIO and AS_ENOSPC flags mm: don't TestClearPageError in __filemap_fdatawait_range buffer: set errors in mapping at the time that the error occurs cifs: cleanup writeback handling errors and comments mm: clean up error handling in write_one_page jbd2: don't reset error in journal_finish_inode_data_buffers gfs2: clean up some filemap_* calls nfs: convert to new errseq_t based error tracking for writeback errors Documentation: flesh out the section in vfs.txt on storing and reporting writeback errors mm: flesh out comments over mapping_set_error mm: clean up comments in me_pagecache_dirty Documentation/filesystems/vfs.txt | 49 +++++++++- drivers/dax/dax.c | 1 + fs/9p/vfs_addr.c | 5 +- fs/block_dev.c | 1 + fs/btrfs/disk-io.c | 6 +- fs/btrfs/disk-io.h | 2 +- fs/btrfs/file.c | 10 +- fs/btrfs/tree-log.c | 9 +- fs/buffer.c | 19 ++-- fs/cifs/cifsfs.c | 4 +- fs/cifs/file.c | 19 ++-- fs/cifs/inode.c | 22 ++--- fs/dax.c | 4 +- fs/exofs/dir.c | 2 +- fs/ext2/dir.c | 2 +- fs/ext2/file.c | 2 +- fs/f2fs/file.c | 3 + fs/f2fs/node.c | 6 +- fs/file_table.c | 1 + fs/fuse/file.c | 8 +- fs/gfs2/glops.c | 17 +--- fs/gfs2/lops.c | 6 +- fs/gfs2/super.c | 6 +- fs/jbd2/commit.c | 13 +-- fs/jfs/jfs_metapage.c | 4 +- fs/libfs.c | 3 + fs/minix/dir.c | 2 +- fs/nfs/file.c | 19 ++-- fs/nfs/inode.c | 5 +- fs/nfs/write.c | 2 +- fs/nilfs2/segment.c | 1 + fs/open.c | 3 + fs/orangefs/file.c | 5 +- fs/sync.c | 13 ++- fs/sysv/dir.c | 2 +- fs/ufs/dir.c | 2 +- include/linux/buffer_head.h | 1 + include/linux/errseq.h | 19 ++++ include/linux/fs.h | 45 +++++++-- include/linux/mm.h | 2 +- include/linux/nfs_fs.h | 3 +- include/linux/pagemap.h | 32 +++--- lib/Makefile | 2 +- lib/errseq.c | 199 ++++++++++++++++++++++++++++++++++++++ mm/filemap.c | 103 ++++++++++++-------- mm/memory-failure.c | 37 ++----- mm/page-writeback.c | 23 +++-- 47 files changed, 512 insertions(+), 232 deletions(-) create mode 100644 include/linux/errseq.h create mode 100644 lib/errseq.c -- 2.9.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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