ext4: use sbi instead of EXT4_SB(sb) in ext4_mb_new_blocks_simple()

Signed-off-by: Lu Hongfei <luhongfei@vivo.com>
Link: https://lore.kernel.org/r/20230707115907.26637-1-luhongfei@vivo.com
Signed-of

ext4: use sbi instead of EXT4_SB(sb) in ext4_mb_new_blocks_simple()

Signed-off-by: Lu Hongfei <luhongfei@vivo.com>
Link: https://lore.kernel.org/r/20230707115907.26637-1-luhongfei@vivo.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: change the type of blocksize in ext4_mb_init_cache()

The return value type of i_blocksize() is 'unsigned int', so the
type of blocksize has been modified from 'int' to 'unsigned int'
to ensure

ext4: change the type of blocksize in ext4_mb_init_cache()

The return value type of i_blocksize() is 'unsigned int', so the
type of blocksize has been modified from 'int' to 'unsigned int'
to ensure data type consistency.

Signed-off-by: Lu Hongfei <luhongfei@vivo.com>
Link: https://lore.kernel.org/r/20230707105516.9156-1-luhongfei@vivo.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: don't use CR_BEST_AVAIL_LEN for non-regular files

Using CR_BEST_AVAIL_LEN only make sense for regular files, as for
non-regular files we never normalize the allocation request length i.e.
goal

ext4: don't use CR_BEST_AVAIL_LEN for non-regular files

Using CR_BEST_AVAIL_LEN only make sense for regular files, as for
non-regular files we never normalize the allocation request length i.e.
goal len is same as original length (ac_g_ex.fe_len == ac_o_ex.fe_len).

Hence there is no scope of trimming the goal length to make it
satisfy original request len. Thus this patch avoids using
CR_BEST_AVAIL_LEN criteria for non-regular files request.

Cc: stable@kernel.org
Fixes: 33122aa930f1 ("ext4: Add allocation criteria 1.5 (CR1_5)")
Reported-by: Eric Whitney <enwlinux@gmail.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Tested-by: Eric Whitney <enwlinux@gmail.com>
Link: https://lore.kernel.org/r/2a694c748ff8b8c4b416995a24f06f07b55047a8.1689516047.git.ritesh.list@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: correct some stale comment of criteria

We named criteria with CR_XXX, correct stale comment to criteria with
raw number.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Rit

ext4: correct some stale comment of criteria

We named criteria with CR_XXX, correct stale comment to criteria with
raw number.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-11-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: return found group directly in ext4_mb_choose_next_group_best_avail

Return good group when it's found in loop to remove futher check if good
group is found after loop.

Signed-off-by: Kemeng S

ext4: return found group directly in ext4_mb_choose_next_group_best_avail

Return good group when it's found in loop to remove futher check if good
group is found after loop.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-10-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: return found group directly in ext4_mb_choose_next_group_goal_fast

Return good group when it's found in loop to remove futher check if good
group is found after loop.

Signed-off-by: Kemeng Sh

ext4: return found group directly in ext4_mb_choose_next_group_goal_fast

Return good group when it's found in loop to remove futher check if good
group is found after loop.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-9-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: replace the traditional ternary conditional operator with with max()/min()

Replace the traditional ternary conditional operator with with max()/min()

Signed-off-by: Kemeng Shi <shikemeng@huaw

ext4: replace the traditional ternary conditional operator with with max()/min()

Replace the traditional ternary conditional operator with with max()/min()

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-7-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: remove unnecessary return for void function

The return at end of void function is unnecessary, just remove it.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjan

ext4: remove unnecessary return for void function

The return at end of void function is unnecessary, just remove it.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-6-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: use is_power_of_2 helper in ext4_mb_regular_allocator

Use intuitive is_power_of_2 helper in ext4_mb_regular_allocator.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Rites

ext4: use is_power_of_2 helper in ext4_mb_regular_allocator

Use intuitive is_power_of_2 helper in ext4_mb_regular_allocator.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-5-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: return found group directly in ext4_mb_choose_next_group_p2_aligned

Return good group when it's found in loop to remove unnecessary NULL
initialization of grp and futher check if good group is

ext4: return found group directly in ext4_mb_choose_next_group_p2_aligned

Return good group when it's found in loop to remove unnecessary NULL
initialization of grp and futher check if good group is found after loop.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-4-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: avoid potential data overflow in next_linear_group

ngroups is ext4_group_t (unsigned int) while next_linear_group treat it
in int. If ngroups is bigger than max number described by int, it wil

ext4: avoid potential data overflow in next_linear_group

ngroups is ext4_group_t (unsigned int) while next_linear_group treat it
in int. If ngroups is bigger than max number described by int, it will
be treat as a negative number. Then "return group + 1 >= ngroups ? 0 :
group + 1;" may keep returning 0.
Switch int to ext4_group_t in next_linear_group to fix the overflow.

Fixes: 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-3-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: correct grp validation in ext4_mb_good_group

Group corruption check will access memory of grp and will trigger kernel
crash if grp is NULL. So do NULL check before corruption check.

Fixes: 53

ext4: correct grp validation in ext4_mb_good_group

Group corruption check will access memory of grp and will trigger kernel
crash if grp is NULL. So do NULL check before corruption check.

Fixes: 5354b2af3406 ("ext4: allow ext4_get_group_info() to fail")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-2-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: replace CR_FAST macro with inline function for readability

Replace CR_FAST with ext4_mb_cr_expensive() inline function for better
readability. This function returns true if the criteria is one

ext4: replace CR_FAST macro with inline function for readability

Replace CR_FAST with ext4_mb_cr_expensive() inline function for better
readability. This function returns true if the criteria is one of the
expensive/slower ones where lots of disk IO/prefetching is acceptable.

No functional changes are intended in this patch.

Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230630085927.140137-1-ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: drop EXT4_MF_FS_ABORTED flag

EXT4_MF_FS_ABORTED flag has practically the same intent as
EXT4_FLAGS_SHUTDOWN flag. The shutdown flag is checked in many more
places than the aborted flag which i

ext4: drop EXT4_MF_FS_ABORTED flag

EXT4_MF_FS_ABORTED flag has practically the same intent as
EXT4_FLAGS_SHUTDOWN flag. The shutdown flag is checked in many more
places than the aborted flag which is mostly the historical artifact
where we were relying on SB_RDONLY checks instead of the aborted flag
checks. There are only three places - ext4_sync_file(),
__ext4_remount(), and mballoc debug code - which check aborted flag and
not shutdown flag and this is arguably a bug. Avoid these
inconsistencies by removing EXT4_MF_FS_ABORTED flag and using
EXT4_FLAGS_SHUTDOWN everywhere.

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230616165109.21695-5-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: avoid overlapping preallocations due to overflow

Let's say we want to allocate 2 blocks starting from 4294966386, after
predicting the file size, start is aligned to 4294965248, len is changed

ext4: avoid overlapping preallocations due to overflow

Let's say we want to allocate 2 blocks starting from 4294966386, after
predicting the file size, start is aligned to 4294965248, len is changed
to 2048, then end = start + size = 0x100000000. Since end is of
type ext4_lblk_t, i.e. uint, end is truncated to 0.

This causes (pa->pa_lstart >= end) to always hold when checking if the
current extent to be allocated crosses already preallocated blocks, so the
resulting ac_g_ex may cross already preallocated blocks. Hence we convert
the end type to loff_t and use pa_logical_end() to avoid overflow.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230724121059.11834-4-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: fix BUG in ext4_mb_new_inode_pa() due to overflow

When we calculate the end position of ext4_free_extent, this position may
be exactly where ext4_lblk_t (i.e. uint) overflows. For example, if

ext4: fix BUG in ext4_mb_new_inode_pa() due to overflow

When we calculate the end position of ext4_free_extent, this position may
be exactly where ext4_lblk_t (i.e. uint) overflows. For example, if
ac_g_ex.fe_logical is 4294965248 and ac_orig_goal_len is 2048, then the
computed end is 0x100000000, which is 0. If ac->ac_o_ex.fe_logical is not
the first case of adjusting the best extent, that is, new_bex_end > 0, the
following BUG_ON will be triggered:

=========================================================
kernel BUG at fs/ext4/mballoc.c:5116!
invalid opcode: 0000 [#1] PREEMPT SMP PTI
CPU: 3 PID: 673 Comm: xfs_io Tainted: G E 6.5.0-rc1+ #279
RIP: 0010:ext4_mb_new_inode_pa+0xc5/0x430
Call Trace:
<TASK>
ext4_mb_use_best_found+0x203/0x2f0
ext4_mb_try_best_found+0x163/0x240
ext4_mb_regular_allocator+0x158/0x1550
ext4_mb_new_blocks+0x86a/0xe10
ext4_ext_map_blocks+0xb0c/0x13a0
ext4_map_blocks+0x2cd/0x8f0
ext4_iomap_begin+0x27b/0x400
iomap_iter+0x222/0x3d0
__iomap_dio_rw+0x243/0xcb0
iomap_dio_rw+0x16/0x80
=========================================================

A simple reproducer demonstrating the problem:

mkfs.ext4 -F /dev/sda -b 4096 100M
mount /dev/sda /tmp/test
fallocate -l1M /tmp/test/tmp
fallocate -l10M /tmp/test/file
fallocate -i -o 1M -l16777203M /tmp/test/file
fsstress -d /tmp/test -l 0 -n 100000 -p 8 &
sleep 10 && killall -9 fsstress
rm -f /tmp/test/tmp
xfs_io -c "open -ad /tmp/test/file" -c "pwrite -S 0xff 0 8192"

We simply refactor the logic for adjusting the best extent by adding
a temporary ext4_free_extent ex and use extent_logical_end() to avoid
overflow, which also simplifies the code.

Cc: stable@kernel.org # 6.4
Fixes: 93cdf49f6eca ("ext4: Fix best extent lstart adjustment logic in ext4_mb_new_inode_pa()")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230724121059.11834-3-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: add two helper functions extent_logical_end() and pa_logical_end()

When we use lstart + len to calculate the end of free extent or prealloc
space, it may exceed the maximum value of 4294967295

ext4: add two helper functions extent_logical_end() and pa_logical_end()

When we use lstart + len to calculate the end of free extent or prealloc
space, it may exceed the maximum value of 4294967295(0xffffffff) supported
by ext4_lblk_t and cause overflow, which may lead to various problems.

Therefore, we add two helper functions, extent_logical_end() and
pa_logical_end(), to limit the type of end to loff_t, and also convert
lstart to loff_t for calculation to avoid overflow.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230724121059.11834-2-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: fix rbtree traversal bug in ext4_mb_use_preallocated

During allocations, while looking for preallocations(PA) in the per
inode rbtree, we can't do a direct traversal of the tree because
ext4_m

ext4: fix rbtree traversal bug in ext4_mb_use_preallocated

During allocations, while looking for preallocations(PA) in the per
inode rbtree, we can't do a direct traversal of the tree because
ext4_mb_discard_group_preallocation() can paralelly mark the pa deleted
and that can cause direct traversal to skip some entries. This was
leading to a BUG_ON() being hit [1] when we missed a PA that could satisfy
our request and ultimately tried to create a new PA that would overlap
with the missed one.

To makes sure we handle that case while still keeping the performance of
the rbtree, we make use of the fact that the only pa that could possibly
overlap the original goal start is the one that satisfies the below
conditions:

1. It must have it's logical start immediately to the left of
(ie less than) original logical start.

2. It must not be deleted

To find this pa we use the following traversal method:

1. Descend into the rbtree normally to find the immediate neighboring
PA. Here we keep descending irrespective of if the PA is deleted or if
it overlaps with our request etc. The goal is to find an immediately
adjacent PA.

2. If the found PA is on right of original goal, use rb_prev() to find
the left adjacent PA.

3. Check if this PA is deleted and keep moving left with rb_prev() until
a non deleted PA is found.

4. This is the PA we are looking for. Now we can check if it can satisfy
the original request and proceed accordingly.

This approach also takes care of having deleted PAs in the tree.

(While we are at it, also fix a possible overflow bug in calculating the
end of a PA)

[1] https://lore.kernel.org/linux-ext4/CA+G9fYv2FRpLqBZf34ZinR8bU2_ZRAUOjKAD3+tKRFaEQHtt8Q@mail.gmail.com/

Cc: stable@kernel.org # 6.4
Fixes: 3872778664e3 ("ext4: Use rbtrees to manage PAs instead of inode i_prealloc_list")
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reviewed-by: Ritesh Harjani (IBM) ritesh.list@gmail.com
Tested-by: Ritesh Harjani (IBM) ritesh.list@gmail.com
Link: https://lore.kernel.org/r/edd2efda6a83e6343c5ace9deea44813e71dbe20.1690045963.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: fix off by one issue in ext4_mb_choose_next_group_best_avail()

In ext4_mb_choose_next_group_best_avail(), we want the start order to be
1 less than goal length and the min_order to be, at max,

ext4: fix off by one issue in ext4_mb_choose_next_group_best_avail()

In ext4_mb_choose_next_group_best_avail(), we want the start order to be
1 less than goal length and the min_order to be, at max, 1 more than the
original length. This commit fixes an off by one issue that arose due to
the fact that 1 << fls(n) > (n).

After all the processing:

order = 1 order below goal len
min_order = maximum of the three:-
- order - trim_order
- 1 order below B2C(s_stripe)
- 1 order above original len

Cc: stable@kernel.org
Fixes: 33122aa930 ("ext4: Add allocation criteria 1.5 (CR1_5)")
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20230609103403.112807-1-ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: clean up mballoc criteria comments

Line wrap and slightly clarify the comments describing mballoc's
cirtiera.

Define EXT4_MB_NUM_CRS as part of the enum, so that it will
automatically get upd

ext4: clean up mballoc criteria comments

Line wrap and slightly clarify the comments describing mballoc's
cirtiera.

Define EXT4_MB_NUM_CRS as part of the enum, so that it will
automatically get updated when criteria is added or removed.

Also fix a potential unitialized use of 'cr' variable if
CONFIG_EXT4_DEBUG is enabled.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: Give symbolic names to mballoc criterias

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

ext4: Give symbolic names to mballoc criterias

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 <jack@suse.cz>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/a2dc6ec5aea5e5e68cf8e788c2a964ffead9c8b0.1685449706.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

show more ...

ext4: Add allocation criteria 1.5 (CR1_5)

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 fin

ext4: Add allocation criteria 1.5 (CR1_5)

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/<partition>/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) <ritesh.list@gmail.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/150fdf65c8e4cc4dba71e020ce0859bcf636a5ff.1685449706.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

show more ...

ext4: Abstract out logic to search average fragment list

Make the logic of searching average fragment list of a given order reusable
by abstracting it out to a differnet function. This will also avo

ext4: Abstract out logic to search average fragment list

Make the logic of searching average fragment list of a given order reusable
by abstracting it out to a differnet function. This will also avoid
code duplication in upcoming patches.

No functional changes.

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/028c11d95b17ce0285f45456709a0ca922df1b83.1685449706.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: Ensure ext4_mb_prefetch_fini() is called for all prefetched BGs

Before this patch, the call stack in ext4_run_li_request is as follows:

/*
* nr = no. of BGs we want to fetch (=s_mb_prefe

ext4: Ensure ext4_mb_prefetch_fini() is called for all prefetched BGs

Before this patch, the call stack in ext4_run_li_request is as follows:

/*
* nr = no. of BGs we want to fetch (=s_mb_prefetch)
* prefetch_ios = no. of BGs not uptodate after
* ext4_read_block_bitmap_nowait()
*/
next_group = ext4_mb_prefetch(sb, group, nr, prefetch_ios);
ext4_mb_prefetch_fini(sb, next_group prefetch_ios);

ext4_mb_prefetch_fini() will only try to initialize buddies for BGs in
range [next_group - prefetch_ios, next_group). This is incorrect since
sometimes (prefetch_ios < nr), which causes ext4_mb_prefetch_fini() to
incorrectly ignore some of the BGs that might need initialization. This
issue is more notable now with the previous patch enabling "fetching" of
BLOCK_UNINIT BGs which are marked buffer_uptodate by default.

Fix this by passing nr to ext4_mb_prefetch_fini() instead of
prefetch_ios so that it considers the right range of groups.

Similarly, make sure we don't pass nr=0 to ext4_mb_prefetch_fini() in
ext4_mb_regular_allocator() since we might have prefetched BLOCK_UNINIT
groups that would need buddy initialization.

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/05e648ae04ec5b754207032823e9c1de9a54f87a.1685449706.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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ext4: Don't skip prefetching BLOCK_UNINIT groups

Currently, ext4_mb_prefetch() and ext4_mb_prefetch_fini() skip
BLOCK_UNINIT groups since fetching their bitmaps doesn't need disk IO.
As a consequenc

ext4: Don't skip prefetching BLOCK_UNINIT groups

Currently, ext4_mb_prefetch() and ext4_mb_prefetch_fini() skip
BLOCK_UNINIT groups since fetching their bitmaps doesn't need disk IO.
As a consequence, we end not initializing the buddy structures and CR0/1
lists for these BGs, even though it can be done without any disk IO
overhead. Hence, don't skip such BGs during prefetch and prefetch_fini.

This improves the accuracy of CR0/1 allocation as earlier, we could have
essentially empty BLOCK_UNINIT groups being ignored by CR0/1 due to their buddy
not being initialized, leading to slower CR2 allocations. With this patch CR0/1
will be able to discover these groups as well, thus improving performance.

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/dc3130b8daf45ffe63d8a3c1edcf00eb8ba70e1f.1685449706.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

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