From: Stefan Roesch <[email protected]>
To: Jan Kara <[email protected]>
Cc: [email protected], [email protected], [email protected],
[email protected], [email protected],
[email protected], [email protected], [email protected]
Subject: Re: [PATCH v7 11/15] fs: Optimization for concurrent file time updates.
Date: Thu, 2 Jun 2022 14:06:28 -0700 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 6/2/22 1:59 AM, Jan Kara wrote:
> On Wed 01-06-22 14:01:37, Stefan Roesch wrote:
>> This introduces the S_PENDING_TIME flag. If an async buffered write
>> needs to update the time, it cannot be processed in the fast path of
>> io-uring. When a time update is pending this flag is set for async
>> buffered writes. Other concurrent async buffered writes for the same
>> file do not need to wait while this time update is pending.
>>
>> This reduces the number of async buffered writes that need to get punted
>> to the io-workers in io-uring.
>>
>> Signed-off-by: Stefan Roesch <[email protected]>
>
> Thinking about this, there is a snag with this S_PENDING_TIME scheme. It
> can happen that we report write as completed to userspace before timestamps
> are actually updated. So following stat(2) can still return old time stamp
> which might confuse some userspace application. It might be even nastier
> with i_version which is used by NFS and can thus cause data consistency
> issues for NFS.
>
Thanks for catching this, I removed this patch from the patch series.
> Honza
>
>> ---
>> fs/inode.c | 11 +++++++++--
>> include/linux/fs.h | 3 +++
>> 2 files changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/inode.c b/fs/inode.c
>> index 4503bed063e7..7185d860d423 100644
>> --- a/fs/inode.c
>> +++ b/fs/inode.c
>> @@ -2150,10 +2150,17 @@ static int file_modified_flags(struct file *file, int flags)
>> ret = inode_needs_update_time(inode, &now);
>> if (ret <= 0)
>> return ret;
>> - if (flags & IOCB_NOWAIT)
>> + if (flags & IOCB_NOWAIT) {
>> + if (IS_PENDING_TIME(inode))
>> + return 0;
>> +
>> + inode_set_flags(inode, S_PENDING_TIME, S_PENDING_TIME);
>> return -EAGAIN;
>> + }
>>
>> - return __file_update_time(file, &now, ret);
>> + ret = __file_update_time(file, &now, ret);
>> + inode_set_flags(inode, 0, S_PENDING_TIME);
>> + return ret;
>> }
>>
>> /**
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index 553e57ec3efa..15f9a7beba55 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -2151,6 +2151,8 @@ struct super_operations {
>> #define S_CASEFOLD (1 << 15) /* Casefolded file */
>> #define S_VERITY (1 << 16) /* Verity file (using fs/verity/) */
>> #define S_KERNEL_FILE (1 << 17) /* File is in use by the kernel (eg. fs/cachefiles) */
>> +#define S_PENDING_TIME (1 << 18) /* File update time is pending */
>> +
>>
>> /*
>> * Note that nosuid etc flags are inode-specific: setting some file-system
>> @@ -2193,6 +2195,7 @@ static inline bool sb_rdonly(const struct super_block *sb) { return sb->s_flags
>> #define IS_ENCRYPTED(inode) ((inode)->i_flags & S_ENCRYPTED)
>> #define IS_CASEFOLDED(inode) ((inode)->i_flags & S_CASEFOLD)
>> #define IS_VERITY(inode) ((inode)->i_flags & S_VERITY)
>> +#define IS_PENDING_TIME(inode) ((inode)->i_flags & S_PENDING_TIME)
>>
>> #define IS_WHITEOUT(inode) (S_ISCHR(inode->i_mode) && \
>> (inode)->i_rdev == WHITEOUT_DEV)
>> --
>> 2.30.2
>>
next prev parent reply other threads:[~2022-06-02 21:06 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-01 21:01 [PATCH v7 00/15] io-uring/xfs: support async buffered writes Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 01/15] mm: Move starting of background writeback into the main balancing loop Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 02/15] mm: Move updates of dirty_exceeded into one place Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 03/15] mm: Add balance_dirty_pages_ratelimited_flags() function Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 04/15] iomap: Add flags parameter to iomap_page_create() Stefan Roesch
2022-06-02 16:26 ` Darrick J. Wong
2022-06-01 21:01 ` [PATCH v7 05/15] iomap: Add async buffered write support Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 06/15] iomap: Return error code from iomap_write_iter() Stefan Roesch
2022-06-02 12:38 ` Matthew Wilcox
2022-06-02 17:08 ` Stefan Roesch
2022-06-06 16:39 ` Stefan Roesch
2022-06-06 19:18 ` Matthew Wilcox
2022-06-06 19:21 ` Stefan Roesch
2022-06-06 19:25 ` Matthew Wilcox
2022-06-06 19:28 ` Stefan Roesch
2022-06-06 20:30 ` Matthew Wilcox
2022-06-06 20:34 ` Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 07/15] fs: Add check for async buffered writes to generic_write_checks Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 08/15] fs: add __remove_file_privs() with flags parameter Stefan Roesch
2022-06-02 9:04 ` Jan Kara
2022-06-01 21:01 ` [PATCH v7 09/15] fs: Split off inode_needs_update_time and __file_update_time Stefan Roesch
2022-06-02 8:44 ` Jan Kara
2022-06-02 12:57 ` Matthew Wilcox
2022-06-02 21:04 ` Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 10/15] fs: Add async write file modification handling Stefan Roesch
2022-06-02 8:44 ` Jan Kara
2022-06-02 9:06 ` Jan Kara
2022-06-02 21:00 ` Stefan Roesch
2022-06-03 10:12 ` Jan Kara
2022-06-06 16:35 ` Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 11/15] fs: Optimization for concurrent file time updates Stefan Roesch
2022-06-02 8:59 ` Jan Kara
2022-06-02 21:06 ` Stefan Roesch [this message]
2022-06-01 21:01 ` [PATCH v7 12/15] io_uring: Add support for async buffered writes Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 13/15] io_uring: Add tracepoint for short writes Stefan Roesch
2022-06-01 21:01 ` [PATCH v7 14/15] xfs: Specify lockmode when calling xfs_ilock_for_iomap() Stefan Roesch
2022-06-02 16:25 ` Darrick J. Wong
2022-06-01 21:01 ` [PATCH v7 15/15] xfs: Add async buffered write support Stefan Roesch
2022-07-01 4:39 ` Al Viro
2022-07-01 14:19 ` Jens Axboe
2022-07-01 14:30 ` Jens Axboe
2022-07-01 14:38 ` Jens Axboe
2022-07-01 18:05 ` Darrick J. Wong
2022-07-01 18:14 ` Jens Axboe
2022-07-05 13:47 ` Josef Bacik
2022-07-05 14:23 ` Goldwyn Rodrigues
2022-07-05 16:11 ` Christoph Hellwig
2022-06-02 8:09 ` [PATCH v7 00/15] io-uring/xfs: support async buffered writes Jens Axboe
2022-06-03 2:43 ` Dave Chinner
2022-06-03 13:04 ` Jens Axboe
2022-06-07 16:41 ` Stefan Roesch
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