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Eric Biggers 315cd8fc2a fs: fix lazytime expiration handling in __writeback_single_inode()
commit 1e249cb5b7 upstream.

When lazytime is enabled and an inode is being written due to its
in-memory updated timestamps having expired, either due to a sync() or
syncfs() system call or due to dirtytime_expire_interval having elapsed,
the VFS needs to inform the filesystem so that the filesystem can copy
the inode's timestamps out to the on-disk data structures.

This is done by __writeback_single_inode() calling
mark_inode_dirty_sync(), which then calls ->dirty_inode(I_DIRTY_SYNC).

However, this occurs after __writeback_single_inode() has already
cleared the dirty flags from ->i_state.  This causes two bugs:

- mark_inode_dirty_sync() redirties the inode, causing it to remain
  dirty.  This wastefully causes the inode to be written twice.  But
  more importantly, it breaks cases where sync_filesystem() is expected
  to clean dirty inodes.  This includes the FS_IOC_REMOVE_ENCRYPTION_KEY
  ioctl (as reported at
  https://lore.kernel.org/r/20200306004555.GB225345@gmail.com), as well
  as possibly filesystem freezing (freeze_super()).

- Since ->i_state doesn't contain I_DIRTY_TIME when ->dirty_inode() is
  called from __writeback_single_inode() for lazytime expiration,
  xfs_fs_dirty_inode() ignores the notification.  (XFS only cares about
  lazytime expirations, and it assumes that i_state will contain
  I_DIRTY_TIME during those.)  Therefore, lazy timestamps aren't
  persisted by sync(), syncfs(), or dirtytime_expire_interval on XFS.

Fix this by moving the call to mark_inode_dirty_sync() to earlier in
__writeback_single_inode(), before the dirty flags are cleared from
i_state.  This makes filesystems be properly notified of the timestamp
expiration, and it avoids incorrectly redirtying the inode.

This fixes xfstest generic/580 (which tests
FS_IOC_REMOVE_ENCRYPTION_KEY) when run on ext4 or f2fs with lazytime
enabled.  It also fixes the new lazytime xfstest I've proposed, which
reproduces the above-mentioned XFS bug
(https://lore.kernel.org/r/20210105005818.92978-1-ebiggers@kernel.org).

Alternatively, we could call ->dirty_inode(I_DIRTY_SYNC) directly.  But
due to the introduction of I_SYNC_QUEUED, mark_inode_dirty_sync() is the
right thing to do because mark_inode_dirty_sync() now knows not to move
the inode to a writeback list if it is currently queued for sync.

Fixes: 0ae45f63d4 ("vfs: add support for a lazytime mount option")
Cc: stable@vger.kernel.org
Depends-on: 5afced3bf2 ("writeback: Avoid skipping inode writeback")
Link: https://lore.kernel.org/r/20210112190253.64307-2-ebiggers@kernel.org
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-30 13:54:11 +01:00
Documentation dm integrity: conditionally disable "recalculate" feature 2021-01-30 13:54:10 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch arm64: mm: use single quantity to represent the PA to VA translation 2021-01-30 13:54:10 +01:00
block bfq: Fix computation of shallow depth 2021-01-19 18:26:15 +01:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto crypto: asym_tpm: correct zero out potential secrets 2021-01-12 20:16:17 +01:00
drivers dm integrity: conditionally disable "recalculate" feature 2021-01-30 13:54:10 +01:00
fs fs: fix lazytime expiration handling in __writeback_single_inode() 2021-01-30 13:54:11 +01:00
include writeback: Drop I_DIRTY_TIME_EXPIRE 2021-01-30 13:54:11 +01:00
init exec: Transform exec_update_mutex into a rw_semaphore 2021-01-09 13:44:55 +01:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel tracing: Fix race in trace_open and buffer resize call 2021-01-30 13:54:10 +01:00
lib lib/raid6: Let $(UNROLL) rules work with macOS userland 2021-01-19 18:26:15 +01:00
mm Revert "mm/slub: fix a memory leak in sysfs_slab_add()" 2021-01-30 13:54:09 +01:00
net tcp: fix TCP_USER_TIMEOUT with zero window 2021-01-27 11:47:55 +01:00
samples samples: bpf: Fix lwt_len_hist reusing previous BPF map 2020-12-30 11:51:12 +01:00
scripts depmod: handle the case of /sbin/depmod without /sbin in PATH 2021-01-12 20:16:10 +01:00
security dump_common_audit_data(): fix racy accesses to ->d_name 2021-01-19 18:26:16 +01:00
sound ASoC: Intel: haswell: Add missing pm_ops 2021-01-27 11:47:42 +01:00
tools tools: Factor HOSTCC, HOSTLD, HOSTAR definitions 2021-01-30 13:54:10 +01:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt kvm: check tlbs_dirty directly 2021-01-12 20:16:22 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.93 2021-01-27 11:47:55 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.