| Age | Commit message (Collapse) | Author |
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Although we now perform ordered traversal within an xarray, this is
currently limited to a single xarray. However, we have multiple such
xarrays, which prevents us from guaranteeing a linear-like traversal
where all groups on the right are visited before all groups on the left.
For example, suppose we have 128 block groups, with a target group of 64,
a target length corresponding to an order of 1, and available free groups
of 16 (order 1) and group 65 (order 8):
For linear traversal, when no suitable free block is found in group 64, it
will search in the next block group until group 127, then start searching
from 0 up to block group 63. It ensures continuous forward traversal, which
is consistent with the unidirectional rotation behavior of HDD platters.
Additionally, the block group lock contention during freeing block is
unavoidable. The goal increasing from 0 to 64 indicates that previously
scanned groups (which had no suitable free space and are likely to free
blocks later) and skipped groups (which are currently in use) have newly
freed some used blocks. If we allocate blocks in these groups, the
probability of competing with other processes increases.
For non-linear traversal, we first traverse all groups in order_1. If only
group 16 has free space in this list, we first traverse [63, 128), then
traverse [0, 64) to find the available group 16, and then allocate blocks
in group 16. Therefore, it cannot guarantee continuous traversal in one
direction, thus increasing the probability of contention.
So refactor ext4_mb_scan_groups_xarray() to ext4_mb_scan_groups_xa_range()
to only traverse a fixed range of groups, and move the logic for handling
wrap around to the caller. The caller first iterates through all xarrays
in the range [start, ngroups) and then through the range [0, start). This
approach simulates a linear scan, which reduces contention between freeing
blocks and allocating blocks.
Assume we have the following groups, where "|" denotes the xarray traversal
start position:
order_1_groups: AB | CD
order_2_groups: EF | GH
Traversal order:
Before: C > D > A > B > G > H > E > F
After: C > D > G > H > A > B > E > F
Performance test data follows:
|CPU: Kunpeng 920 | P80 | P1 |
|Memory: 512GB |------------------------|-------------------------|
|960GB SSD (0.5GB/s)| base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 19555 | 20049 (+2.5%) | 315636 | 316724 (-0.3%) |
|mb_optimize_scan=1 | 15496 | 19342 (+24.8%) | 323569 | 328324 (+1.4%) |
|CPU: AMD 9654 * 2 | P96 | P1 |
|Memory: 1536GB |------------------------|-------------------------|
|960GB SSD (1GB/s) | base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 53192 | 52125 (-2.0%) | 212678 | 215136 (+1.1%) |
|mb_optimize_scan=1 | 37636 | 50331 (+33.7%) | 214189 | 209431 (-2.2%) |
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-18-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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This commit converts the `choose group` logic to `scan group` using
previously prepared helper functions. This allows us to leverage xarrays
for ordered non-linear traversal, thereby mitigating the "bouncing" issue
inherent in the `choose group` mechanism.
This also decouples linear and non-linear traversals, leading to cleaner
and more readable code.
Key changes:
* ext4_mb_choose_next_group() is refactored to ext4_mb_scan_groups().
* Replaced ext4_mb_good_group() with ext4_mb_scan_group() in non-linear
traversals, and related functions now return error codes instead of
group info.
* Added ext4_mb_scan_groups_linear() for performing linear scans starting
from a specific group for a set number of times.
* Linear scans now execute up to sbi->s_mb_max_linear_groups times,
so ac_groups_linear_remaining is removed as it's no longer used.
* ac->ac_criteria is now used directly instead of passing cr around.
Also, ac->ac_criteria is incremented directly after groups scan fails
for the corresponding criteria.
* Since we're now directly scanning groups instead of finding a good group
then scanning, the following variables and flags are no longer needed,
s_bal_cX_groups_considered is sufficient.
s_bal_p2_aligned_bad_suggestions
s_bal_goal_fast_bad_suggestions
s_bal_best_avail_bad_suggestions
EXT4_MB_CR_POWER2_ALIGNED_OPTIMIZED
EXT4_MB_CR_GOAL_LEN_FAST_OPTIMIZED
EXT4_MB_CR_BEST_AVAIL_LEN_OPTIMIZED
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-17-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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While traversing the list, holding a spin_lock prevents load_buddy, making
direct use of ext4_try_lock_group impossible. This can lead to a bouncing
scenario where spin_is_locked(grp_A) succeeds, but ext4_try_lock_group()
fails, forcing the list traversal to repeatedly restart from grp_A.
In contrast, linear traversal directly uses ext4_try_lock_group(),
avoiding this bouncing. Therefore, we need a lockless, ordered traversal
to achieve linear-like efficiency.
Therefore, this commit converts both average fragment size lists and
largest free order lists into ordered xarrays.
In an xarray, the index represents the block group number and the value
holds the block group information; a non-empty value indicates the block
group's presence.
While insertion and deletion complexity remain O(1), lookup complexity
changes from O(1) to O(nlogn), which may slightly reduce single-threaded
performance.
Additionally, xarray insertions might fail, potentially due to memory
allocation issues. However, since we have linear traversal as a fallback,
this isn't a major problem. Therefore, we've only added a warning message
for insertion failures here.
A helper function ext4_mb_find_good_group_xarray() is added to find good
groups in the specified xarray starting at the specified position start,
and when it reaches ngroups-1, it wraps around to 0 and then to start-1.
This ensures an ordered traversal within the xarray.
Performance test results are as follows: Single-process operations
on an empty disk show negligible impact, while multi-process workloads
demonstrate a noticeable performance gain.
|CPU: Kunpeng 920 | P80 | P1 |
|Memory: 512GB |------------------------|-------------------------|
|960GB SSD (0.5GB/s)| base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 20097 | 19555 (-2.6%) | 316141 | 315636 (-0.2%) |
|mb_optimize_scan=1 | 13318 | 15496 (+16.3%) | 325273 | 323569 (-0.5%) |
|CPU: AMD 9654 * 2 | P96 | P1 |
|Memory: 1536GB |------------------------|-------------------------|
|960GB SSD (1GB/s) | base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 53603 | 53192 (-0.7%) | 214243 | 212678 (-0.7%) |
|mb_optimize_scan=1 | 20887 | 37636 (+80.1%) | 213632 | 214189 (+0.2%) |
[ Applied spelling fixes per discussion on the ext4-list see thread
referened in the Link tag. --tytso]
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-16-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Extract ext4_mb_scan_group() to make the code clearer and to
prepare for the later conversion of 'choose group' to 'scan groups'.
No functional changes.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-15-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Extract ext4_mb_might_prefetch() to make the code clearer and to
prepare for the later conversion of 'choose group' to 'scan groups'.
No functional changes.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-14-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Extract __ext4_mb_scan_group() to make the code clearer and to
prepare for the later conversion of 'choose group' to 'scan groups'.
No functional changes.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-13-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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The grp->bb_largest_free_order is updated regardless of whether
mb_optimize_scan is enabled. This can lead to inconsistencies between
grp->bb_largest_free_order and the actual s_mb_largest_free_orders list
index when mb_optimize_scan is repeatedly enabled and disabled via remount.
For example, if mb_optimize_scan is initially enabled, largest free
order is 3, and the group is in s_mb_largest_free_orders[3]. Then,
mb_optimize_scan is disabled via remount, block allocations occur,
updating largest free order to 2. Finally, mb_optimize_scan is re-enabled
via remount, more block allocations update largest free order to 1.
At this point, the group would be removed from s_mb_largest_free_orders[3]
under the protection of s_mb_largest_free_orders_locks[2]. This lock
mismatch can lead to list corruption.
To fix this, whenever grp->bb_largest_free_order changes, we now always
attempt to remove the group from its old order list. However, we only
insert the group into the new order list if `mb_optimize_scan` is enabled.
This approach helps prevent lock inconsistencies and ensures the data in
the order lists remains reliable.
Fixes: 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning")
CC: stable@vger.kernel.org
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-12-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Groups with no free blocks shouldn't be in any average fragment size list.
However, when all blocks in a group are allocated(i.e., bb_fragments or
bb_free is 0), we currently skip updating the average fragment size, which
means the group isn't removed from its previous s_mb_avg_fragment_size[old]
list.
This created "zombie" groups that were always skipped during traversal as
they couldn't satisfy any block allocation requests, negatively impacting
traversal efficiency.
Therefore, when a group becomes completely full, bb_avg_fragment_size_order
is now set to -1. If the old order was not -1, a removal operation is
performed; if the new order is not -1, an insertion is performed.
Fixes: 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning")
CC: stable@vger.kernel.org
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-11-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Attempt to merge ext4_free_data with already inserted free extents prior
to adding new ones. This strategy drastically cuts down the number of
times locks are held.
For example, if prev, new, and next extents are all mergeable, the existing
code (before this patch) requires acquiring the s_md_lock three times:
prev merge into new and free prev // hold lock
next merge into new and free next // hold lock
insert new // hold lock
After the patch, it only needs to be acquired once:
new merge into next and free new // no lock
next merge into prev and free next // hold lock
Performance test data follows:
Test: Running will-it-scale/fallocate2 on CPU-bound containers.
Observation: Average fallocate operations per container per second.
|CPU: Kunpeng 920 | P80 | P1 |
|Memory: 512GB |------------------------|-------------------------|
|960GB SSD (0.5GB/s)| base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 20043 | 20097 (+0.2%) | 314331 | 316141 (+0.5%) |
|mb_optimize_scan=1 | 7290 | 13318 (+87.4%) | 324226 | 325273 (+0.3%) |
|CPU: AMD 9654 * 2 | P96 | P1 |
|Memory: 1536GB |------------------------|-------------------------|
|960GB SSD (1GB/s) | base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 54999 | 53603 (-2.5%) | 214380 | 214243 (-0.06%)|
|mb_optimize_scan=1 | 13497 | 20887 (+54.6%) | 216276 | 213632 (-1.2%) |
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-10-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Previously, s_md_lock was used to protect s_mb_free_pending during
modifications, while smp_mb() ensured fresh reads, so s_md_lock just
guarantees the atomicity of s_mb_free_pending. Thus we optimized it by
converting s_mb_free_pending into an atomic variable, thereby eliminating
s_md_lock and minimizing lock contention. This also prepares for future
lockless merging of free extents.
Following this modification, s_md_lock is exclusively responsible for
managing insertions and deletions within s_freed_data_list, along with
operations involving list_splice.
Performance test data follows:
Test: Running will-it-scale/fallocate2 on CPU-bound containers.
Observation: Average fallocate operations per container per second.
|CPU: Kunpeng 920 | P80 | P1 |
|Memory: 512GB |------------------------|-------------------------|
|960GB SSD (0.5GB/s)| base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 19628 | 20043 (+2.1%) | 320885 | 314331 (-2.0%) |
|mb_optimize_scan=1 | 7129 | 7290 (+2.2%) | 321275 | 324226 (+0.9%) |
|CPU: AMD 9654 * 2 | P96 | P1 |
|Memory: 1536GB |------------------------|-------------------------|
|960GB SSD (1GB/s) | base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 53760 | 54999 (+2.3%) | 213145 | 214380 (+0.5%) |
|mb_optimize_scan=1 | 12716 | 13497 (+6.1%) | 215262 | 216276 (+0.4%) |
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-9-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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When allocating data blocks, if the first try (goal allocation) fails and
stream allocation is on, it tries a global goal starting from the last
group we used (s_mb_last_group). This helps cluster large files together
to reduce free space fragmentation, and the data block contiguity also
accelerates write-back to disk.
However, when multiple processes allocate blocks, having just one global
goal means they all fight over the same group. This drastically lowers
the chances of extents merging and leads to much worse file fragmentation.
To mitigate this multi-process contention, we now employ multiple global
goals, with the number of goals being the minimum between the number of
possible CPUs and one-quarter of the filesystem's total block group count.
To ensure a consistent goal for each inode, we select the corresponding
goal by taking the inode number modulo the total number of goals.
Performance test data follows:
Test: Running will-it-scale/fallocate2 on CPU-bound containers.
Observation: Average fallocate operations per container per second.
|CPU: Kunpeng 920 | P80 | P1 |
|Memory: 512GB |------------------------|-------------------------|
|960GB SSD (0.5GB/s)| base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 9636 | 19628 (+103%) | 337597 | 320885 (-4.9%) |
|mb_optimize_scan=1 | 4834 | 7129 (+47.4%) | 341440 | 321275 (-5.9%) |
|CPU: AMD 9654 * 2 | P96 | P1 |
|Memory: 1536GB |------------------------|-------------------------|
|960GB SSD (1GB/s) | base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 22341 | 53760 (+140%) | 219707 | 213145 (-2.9%) |
|mb_optimize_scan=1 | 9177 | 12716 (+38.5%) | 215732 | 215262 (+0.2%) |
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-6-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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After we optimized the block group lock, we found another lock
contention issue when running will-it-scale/fallocate2 with multiple
processes. The fallocate's block allocation and the truncate's block
release were fighting over the s_md_lock. The problem is, this lock
protects totally different things in those two processes: the list of
freed data blocks (s_freed_data_list) when releasing, and where to start
looking for new blocks (mb_last_group) when allocating.
Now we only need to track s_mb_last_group and no longer need to track
s_mb_last_start, so we don't need the s_md_lock lock to ensure that the
two are consistent. Since s_mb_last_group is merely a hint and doesn't
require strong synchronization, READ_ONCE/WRITE_ONCE is sufficient.
Besides, the s_mb_last_group data type only requires ext4_group_t
(i.e., unsigned int), rendering unsigned long superfluous.
Performance test data follows:
Test: Running will-it-scale/fallocate2 on CPU-bound containers.
Observation: Average fallocate operations per container per second.
|CPU: Kunpeng 920 | P80 | P1 |
|Memory: 512GB |------------------------|-------------------------|
|960GB SSD (0.5GB/s)| base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 4821 | 9636 (+99.8%) | 314065 | 337597 (+7.4%) |
|mb_optimize_scan=1 | 4784 | 4834 (+1.04%) | 316344 | 341440 (+7.9%) |
|CPU: AMD 9654 * 2 | P96 | P1 |
|Memory: 1536GB |------------------------|-------------------------|
|960GB SSD (1GB/s) | base | patched | base | patched |
|-------------------|-------|----------------|--------|----------------|
|mb_optimize_scan=0 | 15371 | 22341 (+45.3%) | 205851 | 219707 (+6.7%) |
|mb_optimize_scan=1 | 6101 | 9177 (+50.4%) | 207373 | 215732 (+4.0%) |
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-5-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Since stream allocation does not use ac->ac_f_ex.fe_start, it is set to -1
by default, so the no longer needed sbi->s_mb_last_start is removed.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-4-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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In ext4_mb_regular_allocator(), after the call to ext4_mb_find_by_goal()
fails to achieve the inode goal, allocation continues with the stream
allocation global goal. Currently, hits for both are combined in
sbi->s_bal_goals, hindering accurate optimization.
This commit separates global goal hits into sbi->s_bal_stream_goals. Since
stream allocation doesn't use ac->ac_g_ex.fe_start, set fe_start to -1.
This prevents stream allocations from being counted in s_bal_goals. Also
clear EXT4_MB_HINT_TRY_GOAL to avoid calling ext4_mb_find_by_goal again.
After adding `stream_goal_hits`, `/proc/fs/ext4/sdx/mb_stats` will show:
mballoc:
reqs: 840347
success: 750992
groups_scanned: 1230506
cr_p2_aligned_stats:
hits: 21531
groups_considered: 411664
extents_scanned: 21531
useless_loops: 0
bad_suggestions: 6
cr_goal_fast_stats:
hits: 111222
groups_considered: 1806728
extents_scanned: 467908
useless_loops: 0
bad_suggestions: 13
cr_best_avail_stats:
hits: 36267
groups_considered: 1817631
extents_scanned: 156143
useless_loops: 0
bad_suggestions: 204
cr_goal_slow_stats:
hits: 106396
groups_considered: 5671710
extents_scanned: 22540056
useless_loops: 123747
cr_any_free_stats:
hits: 138071
groups_considered: 724692
extents_scanned: 23615593
useless_loops: 585
extents_scanned: 46804261
goal_hits: 1307
stream_goal_hits: 236317
len_goal_hits: 155549
2^n_hits: 21531
breaks: 225096
lost: 35062
buddies_generated: 40/40
buddies_time_used: 48004
preallocated: 5962467
discarded: 4847560
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-3-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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When ext4 allocates blocks, we used to just go through the block groups
one by one to find a good one. But when there are tons of block groups
(like hundreds of thousands or even millions) and not many have free space
(meaning they're mostly full), it takes a really long time to check them
all, and performance gets bad. So, we added the "mb_optimize_scan" mount
option (which is on by default now). It keeps track of some group lists,
so when we need a free block, we can just grab a likely group from the
right list. This saves time and makes block allocation much faster.
But when multiple processes or containers are doing similar things, like
constantly allocating 8k blocks, they all try to use the same block group
in the same list. Even just two processes doing this can cut the IOPS in
half. For example, one container might do 300,000 IOPS, but if you run two
at the same time, the total is only 150,000.
Since we can already look at block groups in a non-linear way, the first
and last groups in the same list are basically the same for finding a block
right now. Therefore, add an ext4_try_lock_group() helper function to skip
the current group when it is locked by another process, thereby avoiding
contention with other processes. This helps ext4 make better use of having
multiple block groups.
Also, to make sure we don't skip all the groups that have free space
when allocating blocks, we won't try to skip busy groups anymore when
ac_criteria is CR_ANY_FREE.
Performance test data follows:
Test: Running will-it-scale/fallocate2 on CPU-bound containers.
Observation: Average fallocate operations per container per second.
|CPU: Kunpeng 920 | P80 |
|Memory: 512GB |-------------------------|
|960GB SSD (0.5GB/s)| base | patched |
|-------------------|-------|-----------------|
|mb_optimize_scan=0 | 2667 | 4821 (+80.7%) |
|mb_optimize_scan=1 | 2643 | 4784 (+81.0%) |
|CPU: AMD 9654 * 2 | P96 |
|Memory: 1536GB |-------------------------|
|960GB SSD (1GB/s) | base | patched |
|-------------------|-------|-----------------|
|mb_optimize_scan=0 | 3450 | 15371 (+345%) |
|mb_optimize_scan=1 | 3209 | 6101 (+90.0%) |
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250714130327.1830534-2-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Enable ext4_free_blocks() to use it, which has a cond_resched to begin
with. Convert to the new nonatomic flavor to benefit from potential
performance benefits and adapt in the future vs migration such that
semantics are kept.
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://kdevops.org/ext4/v6.15-rc2.html # [0]
Link: https://lore.kernel.org/all/aAAEvcrmREWa1SKF@bombadil.infradead.org/ # [1]
Link: https://lore.kernel.org/20250418015921.132400-7-dave@stgolabs.net
Tested-by: kdevops@lists.linux.dev
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.
Use the `DEFINE_RAW_FLEX()` helper for an on-stack definition of
a flexible structure where the size of the flexible-array member
is known at compile-time, and refactor the rest of the code,
accordingly.
So, with these changes, fix the following warning:
fs/ext4/mballoc.c:3041:40: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/Z-SF97N3AxcIMlSi@kspp
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Commit 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning") introduces
the sysfs control interface "mb_max_linear_groups" to address the problem
that rotational devices performance degrades when the "mb_optimize_scan"
feature is enabled, which may result in distant block group allocation.
However, the name of the interface was incorrect in the comment to the
ext4/mballoc.c file, and this patch fixes it, without further changes.
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250224012005.689549-1-wozizhi@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Since both SHUTDOWN and EMERGENCY_RO are emergency states of the ext4 file
system, and they are checked in similar locations, we have added a helper
function, ext4_emergency_state(), to determine whether the current file
system is in one of these two emergency states.
Then, replace calls to ext4_forced_shutdown() with ext4_emergency_state()
in those functions that could potentially trigger write operations.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250122114130.229709-4-libaokun@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Remove hard-coded strings by using the str_yes_no() helper function.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20241021100056.5521-2-thorsten.blum@linux.dev
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Use string choice helpers for better readability and to fix cocci warning
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Julia Lawall <julia.lawall@inria.fr>
Closes: https://lore.kernel.org/r/202410062256.BoynX3c2-lkp@intel.com/
Signed-off-by: R Sundar <prosunofficial@gmail.com>
Link: https://patch.msgid.link/20241007172006.83339-1-prosunofficial@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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The original implementation ext4's FS_IOC_GETFSMAP handling only
worked when the range of queried blocks included at least one free
(unallocated) block range. This is because how the metadata blocks
were emitted was as a side effect of ext4_mballoc_query_range()
calling ext4_getfsmap_datadev_helper(), and that function was only
called when a free block range was identified. As a result, this
caused generic/365 to fail.
Fix this by creating a new function ext4_getfsmap_meta_helper() which
gets called so that blocks before the first free block range in a
block group can get properly reported.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
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Although we have checks to make sure s_stripe is a multiple of cluster
size, in case we accidentally end up with a scenario where this is not
the case, use EXT4_NUM_B2C() so that we don't end up with unexpected
cases where EXT4_B2C(stripe) becomes 0.
Also make the is_stripe_aligned check in regular_allocator a bit more
robust while we are at it. This should ideally have no functional change
unless we have a bug somewhere causing (stripe % cluster_size != 0)
Reviewed-by: Kemeng Shi <shikemeng@huaweicloud.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://patch.msgid.link/e0c0a3b58a40935a1361f668851d041575861411.1725002410.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Commit 3d56b8d2c74c ("ext4: Speed up FITRIM by recording flags in
ext4_group_info") speed up fstrim by skipping trim trimmed group. We
also has the chance to clear trimmed once there exists some block free
for this group(mount without discard), and the next trim for this group
will work well too.
For mount with discard, we will issue dicard when we free blocks, so
leave trimmed flag keep alive to skip useless trim trigger from
userspace seems reasonable. But for some case like ext4 build on
dm-thinpool(ext4 blocksize 4K, pool blocksize 128K), discard from ext4
maybe unaligned for dm thinpool, and thinpool will just finish this
discard(see process_discard_bio when begein equals to end) without
actually process discard. For this case, trim from userspace can really
help us to free some thinpool block.
So convert to clear trimmed flag for all case no matter mounted with
discard or not.
Fixes: 3d56b8d2c74c ("ext4: Speed up FITRIM by recording flags in ext4_group_info")
Signed-off-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20240817085510.2084444-1-yangerkun@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Single characters (line breaks) should be put into a sequence.
Thus use the corresponding function “seq_putc”.
This issue was transformed by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Link: https://patch.msgid.link/076974ab-4da3-4176-89dc-0514e020c276@web.de
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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This code calls folio_put() on an error pointer which will lead to a
crash. Check for both error pointers and NULL pointers before calling
folio_put().
Fixes: 5eea586b47f0 ("ext4: convert bd_buddy_page to bd_buddy_folio")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/eaafa1d9-a61c-4af4-9f97-d3ad72c60200@moroto.mountain
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Smatch complains "err" can be uninitialized in the caller.
fs/ext4/indirect.c:349 ext4_alloc_branch()
error: uninitialized symbol 'err'.
Set the error to zero on the success path.
Fixes: 8016e29f4362 ("ext4: fast commit recovery path")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/363a4673-0fb8-4adf-b4fb-90a499077276@moroto.mountain
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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This just carries around the bd_buddy_folio so should also be a folio.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20240416172900.244637-6-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
|
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This just carries around the bd_bitmap_folio so should also be a folio.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20240416172900.244637-5-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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All callers now have a folio, so convert this function from operating on
a page to operating on a folio. The folio is assumed to be a single page.
Signe-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20240416172900.244637-4-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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There is no need to make this a multi-page folio, so leave all the
infrastructure around it in pages. But since we're locking it, playing
with its refcount and checking whether it's uptodate, it needs to move
to the folio API.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20240416172900.244637-3-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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There is no need to make this a multi-page folio, so leave all the
infrastructure around it in pages. But since we're locking it, playing
with its refcount and checking whether it's uptodate, it needs to move
to the folio API.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20240416172900.244637-2-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Open coding repeated check in next_linear_group.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240424061904.987525-6-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Use correct criteria name instead stale integer number in comment
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240424061904.987525-5-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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In mb_mark_used, we will find free chunk and mark it inuse. For chunk
in mid of passed range, we could simply mark whole chunk inuse. For chunk
at end of range, we may need to mark a continuous bits at end of part of
chunk inuse and keep rest part of chunk free. To only mark a part of
chunk inuse, we firstly mark whole chunk inuse and then mark a continuous
range at end of chunk free.
Function mb_mark_used does several times of "mb_find_buddy; mb_clear_bit;
..." to mark a continuous range free which can be done by simply calling
ext4_mb_mark_free_simple which free continuous bits in a more effective
way.
Just call ext4_mb_mark_free_simple in mb_mark_used to use existing and
effective code to free continuous blocks in chunk at end of passed range.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240424061904.987525-4-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Keep "prefetch_grp" and "nr" consistent to avoid to call
ext4_mb_prefetch_fini with non-prefetched groups.
When we step into next criteria, "prefetch_grp" is set to prefetch start
of new criteria while "nr" is number of the prefetched group in previous
criteria. If previous criteria and next criteria are both inexpensive
(< CR_GOAL_LEN_SLOW) and prefetch_ios reachs sbi->s_mb_prefetch_limit
in previous criteria, "prefetch_grp" and "nr" will be inconsistent and
may introduce unexpected cost to do ext4_mb_init_group for non-prefetched
groups.
Reset "nr" to 0 when we reset "prefetch_grp" to goal group to keep them
consistent.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240424061904.987525-2-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Running sparse (make C=1) on mballoc.c we get the following warning:
fs/ext4/mballoc.c:3194:13: warning: context imbalance in
'ext4_mb_seq_structs_summary_start' - wrong count at exit
This is because __acquires(&EXT4_SB(sb)->s_mb_rb_lock) was called in
ext4_mb_seq_structs_summary_start(), but s_mb_rb_lock was removed in commit
83e80a6e3543 ("ext4: use buckets for cr 1 block scan instead of rbtree"),
so remove the __acquires to silence the warning.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240319113325.3110393-10-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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We can trigger a slab-out-of-bounds with the following commands:
mkfs.ext4 -F /dev/$disk 10G
mount /dev/$disk /tmp/test
echo 2147483647 > /sys/fs/ext4/$disk/mb_group_prealloc
echo test > /tmp/test/file && sync
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4]
Read of size 8 at addr ffff888121b9d0f0 by task kworker/u2:0/11
CPU: 0 PID: 11 Comm: kworker/u2:0 Tainted: GL 6.7.0-next-20240118 #521
Call Trace:
dump_stack_lvl+0x2c/0x50
kasan_report+0xb6/0xf0
ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4]
ext4_mb_regular_allocator+0x19e9/0x2370 [ext4]
ext4_mb_new_blocks+0x88a/0x1370 [ext4]
ext4_ext_map_blocks+0x14f7/0x2390 [ext4]
ext4_map_blocks+0x569/0xea0 [ext4]
ext4_do_writepages+0x10f6/0x1bc0 [ext4]
[...]
==================================================================
The flow of issue triggering is as follows:
// Set s_mb_group_prealloc to 2147483647 via sysfs
ext4_mb_new_blocks
ext4_mb_normalize_request
ext4_mb_normalize_group_request
ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc
ext4_mb_regular_allocator
ext4_mb_choose_next_group
ext4_mb_choose_next_group_best_avail
mb_avg_fragment_size_order
order = fls(len) - 2 = 29
ext4_mb_find_good_group_avg_frag_lists
frag_list = &sbi->s_mb_avg_fragment_size[order]
if (list_empty(frag_list)) // Trigger SOOB!
At 4k block size, the length of the s_mb_avg_fragment_size list is 14,
but an oversized s_mb_group_prealloc is set, causing slab-out-of-bounds
to be triggered by an attempt to access an element at index 29.
Add a new attr_id attr_clusters_in_group with values in the range
[0, sbi->s_clusters_per_group] and declare mb_group_prealloc as
that type to fix the issue. In addition avoid returning an order
from mb_avg_fragment_size_order() greater than MB_NUM_ORDERS(sb)
and reduce some useless loops.
Fixes: 7e170922f06b ("ext4: Add allocation criteria 1.5 (CR1_5)")
CC: stable@vger.kernel.org
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20240319113325.3110393-5-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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all caller of ext4_issue_discard() would set biop to NULL since
'commit 55cdd0af2bc5 ("ext4: get discard out of jbd2 commit kthread
contex")', it's unnecessary to keep this parameter any more.
Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20240226081731.3224470-1-haowenchao2@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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When ext4 is mounted without journal, with discard mount option, and on
a device not supporting trim, we print error for each and every freed
extent. This is not only useless but actively harmful. Instead ignore
the EOPNOTSUPP error. Trim is only advisory anyway and when the
filesystem has journal we silently ignore trim error as well.
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20240213101601.17463-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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When yangerkun review commit 93cdf49f6eca ("ext4: Fix best extent lstart
adjustment logic in ext4_mb_new_inode_pa()"), it was found that the best
extent did not completely cover the original request after adjusting the
best extent lstart in ext4_mb_new_inode_pa() as follows:
original request: 2/10(8)
normalized request: 0/64(64)
best extent: 0/9(9)
When we check if best ex can be kept at start of goal, ac_o_ex.fe_logical
is 2 less than the adjusted best extent logical end 9, so we think the
adjustment is done. But obviously 0/9(9) doesn't cover 2/10(8), so we
should determine here if the original request logical end is less than or
equal to the adjusted best extent logical end.
In addition, add a comment stating when adjusted best_ex will not cover
the original request, and remove the duplicate assertion because adjusting
lstart makes no change to b_ex.fe_len.
Link: https://lore.kernel.org/r/3630fa7f-b432-7afd-5f79-781bc3b2c5ea@huawei.com
Fixes: 93cdf49f6eca ("ext4: Fix best extent lstart adjustment logic in ext4_mb_new_inode_pa()")
Cc: <stable@kernel.org>
Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20240201141845.1879253-1-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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If one group is marked as block bitmap corrupted, its free blocks cannot
be used and its free count is also deducted from the global
sbi->s_freeclusters_counter. User might be confused about the absent
free space because we can't query the information about corrupted block
groups except unreliable error messages in syslog. So add a hint to show
block bitmap corrupted groups in mb_groups.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240119061154.1525781-1-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
|
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While cat mb_groups for a mounted ext4 image which has some corrupted
group, the string return to userspace was just "I/O error" which confuse
me a lot. Improve it with ext4_decode_error.
Signed-off-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240118042557.380058-2-yangerkun@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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We can just first call ext4_mb_unload_buddy, then copy information from
ext4_group_info. So remove this unused value.
Signed-off-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240118042557.380058-1-yangerkun@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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As 'needed' to trace_ext4_discard_preallocations is always 0 which
is meaningless. Just remove it.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240105092102.496631-10-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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The "needed" controls the number of ext4_prealloc_space to discard in
ext4_discard_preallocations. Function ext4_discard_preallocations is
supposed to discard all non-used preallocated blocks when "needed"
is 0 and now ext4_discard_preallocations is always called with "needed"
= 0. Remove unnecessary parameter "needed" and remove all non-used
preallocated spaces in ext4_discard_preallocations to simplify the
code.
Note: If count of non-used preallocated spaces could be more than
UINT_MAX, there was a memory leak as some non-used preallocated
spaces are left ununsed and this commit will fix it. Otherwise,
there is no behavior change.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240105092102.496631-9-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Remove unused return value of ext4_mb_release_group_pa.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240105092102.496631-8-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
|
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Remove unused return value of ext4_mb_release_inode_pa
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240105092102.496631-7-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
|
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Remove unused return value of ext4_mb_release.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240105092102.496631-6-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
|
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Function ext4_mb_release_context always return 0 and the return value is
never used. Just remove unneeded return value of ext4_mb_release_context.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240105092102.496631-4-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
|
