2021-03-25 03:37:22

by Shreeya Patel

Subject: [PATCH v4 2/5] fs: Check if utf8 encoding is loaded before calling utf8_unload()

utf8_unload is being called if CONFIG_UNICODE is enabled.
The ifdef block doesn't check if utf8 encoding has been loaded
or not before calling the utf8_unload() function.
This is not the expected behavior since it would sometimes lead
to unloading utf8 even before loading it.
Hence, add a condition which will check if sb->encoding is NOT NULL
before calling the utf8_unload().

Reviewed-by: Gabriel Krisman Bertazi <[email protected]>
Signed-off-by: Shreeya Patel <[email protected]>
---
fs/ext4/super.c | 6 ++++--
fs/f2fs/super.c | 9 ++++++---
2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index ad34a37278cd..e438d14f9a87 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1259,7 +1259,8 @@ static void ext4_put_super(struct super_block *sb)
fs_put_dax(sbi->s_daxdev);
fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy);
#ifdef CONFIG_UNICODE
- utf8_unload(sb->s_encoding);
+ if (sb->s_encoding)
+ utf8_unload(sb->s_encoding);
#endif
kfree(sbi);
}
@@ -5165,7 +5166,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
crypto_free_shash(sbi->s_chksum_driver);

#ifdef CONFIG_UNICODE
- utf8_unload(sb->s_encoding);
+ if (sb->s_encoding)
+ utf8_unload(sb->s_encoding);
#endif

#ifdef CONFIG_QUOTA
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 7069793752f1..0a04983c294e 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1430,7 +1430,8 @@ static void f2fs_put_super(struct super_block *sb)
for (i = 0; i < NR_PAGE_TYPE; i++)
kvfree(sbi->write_io[i]);
#ifdef CONFIG_UNICODE
- utf8_unload(sb->s_encoding);
+ if (sb->s_encoding)
+ utf8_unload(sb->s_encoding);
#endif
kfree(sbi);
}
@@ -4073,8 +4074,10 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
kvfree(sbi->write_io[i]);

#ifdef CONFIG_UNICODE
- utf8_unload(sb->s_encoding);
- sb->s_encoding = NULL;
+ if (sb->s_encoding) {
+ utf8_unload(sb->s_encoding);
+ sb->s_encoding = NULL;
+ }
#endif
free_options:
#ifdef CONFIG_QUOTA
--
2.30.1

2021-03-25 19:23:41

by Eric Biggers

Subject: Re: [PATCH v4 2/5] fs: Check if utf8 encoding is loaded before calling utf8_unload()

On Thu, Mar 25, 2021 at 05:38:08AM +0530, Shreeya Patel wrote:
> utf8_unload is being called if CONFIG_UNICODE is enabled.
> The ifdef block doesn't check if utf8 encoding has been loaded
> or not before calling the utf8_unload() function.
> This is not the expected behavior since it would sometimes lead
> to unloading utf8 even before loading it.
> Hence, add a condition which will check if sb->encoding is NOT NULL
> before calling the utf8_unload().
>
> Reviewed-by: Gabriel Krisman Bertazi <[email protected]>
> Signed-off-by: Shreeya Patel <[email protected]>
> ---
> fs/ext4/super.c | 6 ++++--
> fs/f2fs/super.c | 9 ++++++---
> 2 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index ad34a37278cd..e438d14f9a87 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1259,7 +1259,8 @@ static void ext4_put_super(struct super_block *sb)
> fs_put_dax(sbi->s_daxdev);
> fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy);
> #ifdef CONFIG_UNICODE
> - utf8_unload(sb->s_encoding);
> + if (sb->s_encoding)
> + utf8_unload(sb->s_encoding);
> #endif
> kfree(sbi);
> }


What's the benefit of this change? utf8_unload is a no-op when passed a NULL
pointer; why not keep it that way?

- Eric

2021-03-25 19:33:31

by Gabriel Krisman Bertazi

Subject: Re: [PATCH v4 2/5] fs: Check if utf8 encoding is loaded before calling utf8_unload()

Eric Biggers <[email protected]> writes:

> On Thu, Mar 25, 2021 at 05:38:08AM +0530, Shreeya Patel wrote:
>> utf8_unload is being called if CONFIG_UNICODE is enabled.
>> The ifdef block doesn't check if utf8 encoding has been loaded
>> or not before calling the utf8_unload() function.
>> This is not the expected behavior since it would sometimes lead
>> to unloading utf8 even before loading it.
>> Hence, add a condition which will check if sb->encoding is NOT NULL
>> before calling the utf8_unload().
>>
>> Reviewed-by: Gabriel Krisman Bertazi <[email protected]>
>> Signed-off-by: Shreeya Patel <[email protected]>
>> ---
>> fs/ext4/super.c | 6 ++++--
>> fs/f2fs/super.c | 9 ++++++---
>> 2 files changed, 10 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
>> index ad34a37278cd..e438d14f9a87 100644
>> --- a/fs/ext4/super.c
>> +++ b/fs/ext4/super.c
>> @@ -1259,7 +1259,8 @@ static void ext4_put_super(struct super_block *sb)
>> fs_put_dax(sbi->s_daxdev);
>> fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy);
>> #ifdef CONFIG_UNICODE
>> - utf8_unload(sb->s_encoding);
>> + if (sb->s_encoding)
>> + utf8_unload(sb->s_encoding);
>> #endif
>> kfree(sbi);
>> }
>
>
> What's the benefit of this change? utf8_unload is a no-op when passed a NULL
> pointer; why not keep it that way?

For the record, it no longer is a no-op after patch 5 of this series.
Honestly, I prefer making it explicitly at the caller that we are not
entering the function, like the patch does, instead of returning from it
immediately. Makes it more readable, IMO.

--
Gabriel Krisman Bertazi