linux-toradex.git/fs/ext4/sysfs.c, branch v6.7

ext4: Give symbolic names to mballoc criterias

2023-06-26T23:34:56+00:00

mballoc criterias have historically been called by numbers
like CR0, CR1... however this makes it confusing to understand
what each criteria is about.

Change these criterias from numbers to symbolic names and add
relevant comments. While we are at it, also reformat and add some
comments to ext4_seq_mb_stats_show() for better readability.

Additionally, define CR_FAST which signifies the criteria
below which we can make quicker decisions like:
  * quitting early if (free block < requested len)
  * avoiding to scan free extents smaller than required len.
  * avoiding to initialize buddy cache and work with existing cache
  * limiting prefetches

Suggested-by: Jan Kara 
Signed-off-by: Ojaswin Mujoo 
Link: https://lore.kernel.org/r/a2dc6ec5aea5e5e68cf8e788c2a964ffead9c8b0.1685449706.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o

ext4: Add allocation criteria 1.5 (CR1_5)

2023-06-26T23:34:56+00:00

CR1_5 aims to optimize allocations which can't be satisfied in CR1. The
fact that we couldn't find a group in CR1 suggests that it would be
difficult to find a continuous extent to compleltely satisfy our
allocations. So before falling to the slower CR2, in CR1.5 we
proactively trim the the preallocations so we can find a group with
(free / fragments) big enough.  This speeds up our allocation at the
cost of slightly reduced preallocation.

The patch also adds a new sysfs tunable:

* /sys/fs/ext4//mb_cr1_5_max_trim_order

This controls how much CR1.5 can trim a request before falling to CR2.
For example, for a request of order 7 and max trim order 2, CR1.5 can
trim this upto order 5.

Suggested-by: Ritesh Harjani (IBM) 
Signed-off-by: Ojaswin Mujoo 
Reviewed-by: Ritesh Harjani (IBM) 
Link: https://lore.kernel.org/r/150fdf65c8e4cc4dba71e020ce0859bcf636a5ff.1685449706.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o

ext4: Remove the logic to trim inode PAs

2023-04-06T05:13:13+00:00

Earlier, inode PAs were stored in a linked list. This caused a need to
periodically trim the list down inorder to avoid growing it to a very
large size, as this would severly affect performance during list
iteration.

Recent patches changed this list to an rbtree, and since the tree scales
up much better, we no longer need to have the trim functionality, hence
remove it.

Signed-off-by: Ojaswin Mujoo 
Reviewed-by: Ritesh Harjani (IBM) 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/c409addceaa3ade4b40328e28e3b54b2f259689e.1679731817.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o

ext4: make kobj_type structures constant

2023-03-08T01:20:48+00:00

Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.

Take advantage of this to constify the structure definitions to prevent
modification at runtime.

Signed-off-by: Thomas Weißschuh 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20230209-kobj_type-ext4-v1-1-6865fb05c1f8@weissschuh.net
Signed-off-by: Theodore Ts'o

ext4: fix function prototype mismatch for ext4_feat_ktype

2023-02-19T05:09:59+00:00

With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
indirect call targets are validated against the expected function
pointer prototype to make sure the call target is valid to help mitigate
ROP attacks. If they are not identical, there is a failure at run time,
which manifests as either a kernel panic or thread getting killed.

ext4_feat_ktype was setting the "release" handler to "kfree", which
doesn't have a matching function prototype. Add a simple wrapper
with the correct prototype.

This was found as a result of Clang's new -Wcast-function-type-strict
flag, which is more sensitive than the simpler -Wcast-function-type,
which only checks for type width mismatches.

Note that this code is only reached when ext4 is a loadable module and
it is being unloaded:

 CFI failure at kobject_put+0xbb/0x1b0 (target: kfree+0x0/0x180; expected type: 0x7c4aa698)
 ...
 RIP: 0010:kobject_put+0xbb/0x1b0
 ...
 Call Trace:
  
  ext4_exit_sysfs+0x14/0x60 [ext4]
  cleanup_module+0x67/0xedb [ext4]

Fixes: b99fee58a20a ("ext4: create ext4_feat kobject dynamically")
Cc: Theodore Ts'o 
Cc: Eric Biggers 
Cc: stable@vger.kernel.org
Build-tested-by: Gustavo A. R. Silva 
Reviewed-by: Gustavo A. R. Silva 
Reviewed-by: Nathan Chancellor 
Link: https://lore.kernel.org/r/20230103234616.never.915-kees@kernel.org
Signed-off-by: Kees Cook 
Reviewed-by: Eric Biggers 
Link: https://lore.kernel.org/r/20230104210908.gonna.388-kees@kernel.org
Signed-off-by: Theodore Ts'o

unicode: clean up the Kconfig symbol confusion

2022-01-21T00:57:24+00:00

Turn the CONFIG_UNICODE symbol into a tristate that generates some always
built in code and remove the confusing CONFIG_UNICODE_UTF8_DATA symbol.

Note that a lot of the IS_ENABLED() checks could be turned from cpp
statements into normal ifs, but this change is intended to be fairly
mechanic, so that should be cleaned up later.

Fixes: 2b3d04787012 ("unicode: Add utf8-data module")
Reported-by: Linus Torvalds 
Reviewed-by: Eric Biggers 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Gabriel Krisman Bertazi

ext4: allow to change s_last_trim_minblks via sysfs

2022-01-10T18:25:55+00:00

Ext4 has an optimization mechanism for batched disacrd (FITRIM) that
should help speed up subsequent calls of FITRIM ioctl by skipping the
groups that were previously trimmed. However because the FITRIM allows
to set the minimum size of an extent to trim, ext4 stores the last
minimum extent size and only avoids trimming the group if it was
previously trimmed with minimum extent size equal to, or smaller than
the current call.

There is currently no way to bypass the optimization without
umount/mount cycle. This becomes a problem when the file system is
live migrated to a different storage, because the optimization will
prevent possibly useful discard calls to the storage.

Fix it by exporting the s_last_trim_minblks via sysfs interface which
will allow us to set the minimum size to the number of blocks larger
than subsequent FITRIM call, effectively bypassing the optimization.

By setting the s_last_trim_minblks to ULONG_MAX the optimization will be
effectively cleared regardless of the previous state, or file system
configuration.

For example:
getconf ULONG_MAX > /sys/fs/ext4/dm-1/last_trim_minblks

Signed-off-by: Lukas Czerner 
Reported-by: Laurent GUERBY 
Reviewed-by: Andreas Dilger 
Link: https://lore.kernel.org/r/20211103145122.17338-2-lczerner@redhat.com
Signed-off-by: Theodore Ts'o

ext4: replace snprintf in show functions with sysfs_emit

2022-01-10T18:25:55+00:00

coccicheck complains about the use of snprintf() in sysfs show functions.

Fix the coccicheck warning:
WARNING: use scnprintf or sprintf.

Use sysfs_emit instead of scnprintf or sprintf makes more sense.

Signed-off-by: Qing Wang 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/1634095731-4528-1-git-send-email-wangqing@vivo.com
Signed-off-by: Theodore Ts'o

ext4: notify sysfs on errors_count value change

2021-06-30T01:06:02+00:00

After s_error_count is incremented, signal the change in the
corresponding sysfs attribute via sysfs_notify. This allows userspace to
poll() on changes to /sys/fs/ext4/*/errors_count.

[ Moved call of ext4_notify_error_sysfs() to flush_stashed_error_work()
  to avoid BUG's caused by calling sysfs_notify trying to sleep after
  being called from an invalid context. -- TYT ]

Signed-off-by: Jonathan Davies 
Link: https://lore.kernel.org/r/20210611140209.28903-1-jonathan.davies@nutanix.com
Signed-off-by: Theodore Ts'o

ext4: Only advertise encrypted_casefold when encryption and unicode are enabled

2021-06-06T14:10:23+00:00

Encrypted casefolding is only supported when both encryption and
casefolding are both enabled in the config.

Fixes: 471fbbea7ff7 ("ext4: handle casefolding with encryption")
Cc: stable@vger.kernel.org # 5.13+
Signed-off-by: Daniel Rosenberg 
Link: https://lore.kernel.org/r/20210603094849.314342-1-drosen@google.com
Signed-off-by: Theodore Ts'o