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Zhang Yi dd064d5101 ext4: introduce seq counter for the extent status entry
In the iomap_write_iter(), the iomap buffered write frame does not hold
any locks between querying the inode extent mapping info and performing
page cache writes. As a result, the extent mapping can be changed due to
concurrent I/O in flight. Similarly, in the iomap_writepage_map(), the
write-back process faces a similar problem: concurrent changes can
invalidate the extent mapping before the I/O is submitted.

Therefore, both of these processes must recheck the mapping info after
acquiring the folio lock. To address this, similar to XFS, we propose
introducing an extent sequence number to serve as a validity cookie for
the extent. After commit 24b7a2331f ("ext4: clairfy the rules for
modifying extents"), we can ensure the extent information should always
be processed through the extent status tree, and the extent status tree
is always uptodate under i_rwsem or invalidate_lock or folio lock, so
it's safe to introduce this sequence number. The sequence number will be
increased whenever the extent status tree changes, preparing for the
buffered write iomap conversion.

Besides, this mechanism is also applicable for the moving extents case.
In move_extent_per_page(), it also needs to reacquire data_sem and check
the mapping info again under the folio lock.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-ID: <20251013015128.499308-3-yi.zhang@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2025-11-06 10:44:39 -05:00
Documentation sound fixes for 6.18-rc4 2025-10-31 07:29:09 -07:00
LICENSES
arch Miscellaneous fixes: 2025-11-01 10:20:07 -07:00
block block-6.18-20251031 2025-10-31 12:57:19 -07:00
certs
crypto This push contains the following changes: 2025-10-10 08:56:16 -07:00
drivers spi: Fix for v6.18 2025-11-01 10:50:43 -07:00
fs ext4: introduce seq counter for the extent status entry 2025-11-06 10:44:39 -05:00
include ext4: introduce seq counter for the extent status entry 2025-11-06 10:44:39 -05:00
init
io_uring io_uring: fix buffer auto-commit for multishot uring_cmd 2025-10-23 19:41:31 -06:00
ipc
kernel bpf-fixes 2025-10-31 18:22:26 -07:00
lib Second round of Kbuild fixes for 6.19 2025-11-01 10:00:53 -07:00
mm slab fixes for 6.18-rc3 2025-10-24 12:40:51 -07:00
net bpf-fixes 2025-10-31 18:22:26 -07:00
rust Driver core fixes for 6.18-rc3 2025-10-25 11:03:46 -07:00
samples Char/Misc/IIO/Binder changes for 6.18-rc1 2025-10-04 16:26:32 -07:00
scripts kconfig/nconf: Initialize the default locale at startup 2025-11-01 00:23:22 -04:00
security integrity-v6.18 2025-10-05 10:48:33 -07:00
sound ASoC: Fixes for v6.18 2025-10-30 13:08:08 +01:00
tools objtool: Fix skip_alt_group() for non-alternative STAC/CLAC 2025-11-01 07:43:20 +01:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM x86 fixes for 6.18: 2025-10-18 10:25:43 +02:00
.clang-format
.clippy.toml
.cocciconfig
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COPYING
CREDITS MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild
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MAINTAINERS Second round of Kbuild fixes for 6.19 2025-11-01 10:00:53 -07:00
Makefile Linux 6.18-rc4 2025-11-02 11:28:02 -08:00
README

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 reStructuredText 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.