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Ojaswin Mujoo 93cdf49f6e ext4: Fix best extent lstart adjustment logic in ext4_mb_new_inode_pa()
When the length of best extent found is less than the length of goal extent
we need to make sure that the best extent atleast covers the start of the
original request. This is done by adjusting the ac_b_ex.fe_logical (logical
start) of the extent.

While doing so, the current logic sometimes results in the best extent's
logical range overflowing the goal extent. Since this best extent is later
added to the inode preallocation list, we have a possibility of introducing
overlapping preallocations. This is discussed in detail here [1].

As per Jan's suggestion, to fix this, replace the existing logic with the
below logic for adjusting best extent as it keeps fragmentation in check
while ensuring logical range of best extent doesn't overflow out of goal
extent:

1. Check if best extent can be kept at end of goal range and still cover
   original start.
2. Else, check if best extent can be kept at start of goal range and still
   cover original start.
3. Else, keep the best extent at start of original request.

Also, add a few extra BUG_ONs that might help catch errors faster.

[1] https://lore.kernel.org/r/Y+OGkVvzPN0RMv0O@li-bb2b2a4c-3307-11b2-a85c-8fa5c3a69313.ibm.com

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/f96aca6d415b36d1f90db86c1a8cd7e2e9d7ab0e.1679731817.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2023-04-06 01:13:13 -04:00
arch - Flush out logged errors immediately after MCA banks configuration 2023-03-19 09:57:53 -07:00
block block: remove obsolete config BLOCK_COMPAT 2023-03-16 09:35:44 -06:00
certs Kbuild updates for v6.3 2023-02-26 11:53:25 -08:00
crypto Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
Documentation Including fixes from netfilter, wifi and ipsec. 2023-03-17 13:31:16 -07:00
drivers TTY/Serial driver fixes for 6.3-rc3 2023-03-19 10:09:58 -07:00
fs ext4: Fix best extent lstart adjustment logic in ext4_mb_new_inode_pa() 2023-04-06 01:13:13 -04:00
include ext4: Convert data=journal writeback to use ext4_writepages() 2023-03-23 10:06:08 -04:00
init Kbuild updates for v6.3 2023-02-26 11:53:25 -08:00
io_uring io_uring/rsrc: fix folio accounting 2023-03-16 09:32:18 -06:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel Tracing fixes for 6.3: 2023-03-19 10:46:02 -07:00
lib Zstd fixes for v6.3 2023-03-14 17:03:25 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/damon/paddr: fix folio_nr_pages() after folio_put() in damon_pa_mark_accessed_or_deactivate() 2023-03-07 17:04:55 -08:00
net Including fixes from netfilter, wifi and ipsec. 2023-03-17 13:31:16 -07:00
rust Rust fixes for 6.3-rc1 2023-03-03 14:51:15 -08:00
samples LoongArch changes for v6.3 2023-03-01 09:27:00 -08:00
scripts kbuild: use git-archive for source package creation 2023-03-16 22:46:12 +09:00
security capability: just use a 'u64' instead of a 'u32[2]' array 2023-03-01 10:01:22 -08:00
sound ALSA: hda/ca0132: fixup buffer overrun at tuning_ctl_set() 2023-03-14 17:04:53 +01:00
tools Including fixes from netfilter, wifi and ipsec. 2023-03-17 13:31:16 -07:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM/riscv changes for 6.3 2023-02-15 12:33:28 -05:00
.clang-format cpumask: re-introduce constant-sized cpumask optimizations 2023-03-05 14:30:34 -08:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore kbuild: rpm-pkg: move source components to rpmbuild/SOURCES 2023-03-16 22:45:56 +09:00
.mailmap Including fixes from netfilter, wifi and ipsec. 2023-03-17 13:31:16 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS There is no particular theme here - mainly quick hits all over the tree. 2023-02-23 17:55:40 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS fbdev updates for kernel 6.3-rc3: 2023-03-18 16:01:34 -07:00
Makefile Linux 6.3-rc3 2023-03-19 13:27:55 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.