Chao Yu via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>
于2025年3月24日周一 19:36写道：
>
> This patch uses i_sem to protect access/update on f2fs_inode_info.flag
> in finish_preallocate_blocks(), it avoids grabbing inode_lock() in
> each open().
>
> Signed-off-by: Chao Yu <c...@kernel.org>
> ---
> fs/f2fs/file.c | 40 +++++++++++++++++++++++-----------------
> 1 file changed, 23 insertions(+), 17 deletions(-)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index abbcbb5865a3..bb6ba3269de0 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -554,19 +554,24 @@ static int f2fs_file_mmap(struct file *file, struct
> vm_area_struct *vma)
>
> static int finish_preallocate_blocks(struct inode *inode)
> {
> - int ret;
> + int ret = 0;
> + bool opened;
>
> - inode_lock(inode);
> - if (is_inode_flag_set(inode, FI_OPENED_FILE)) {
> - inode_unlock(inode);
> + f2fs_down_read(&F2FS_I(inode)->i_sem);
> + opened = is_inode_flag_set(inode, FI_OPENED_FILE);
> + f2fs_up_read(&F2FS_I(inode)->i_sem);
> + if (opened)
> return 0;
> - }
>
> - if (!file_should_truncate(inode)) {
> - set_inode_flag(inode, FI_OPENED_FILE);
> - inode_unlock(inode);
> - return 0;
> - }
> + inode_lock(inode);
> + f2fs_down_read(&F2FS_I(inode)->i_sem);
> + opened = is_inode_flag_set(inode, FI_OPENED_FILE);
> + f2fs_up_read(&F2FS_I(inode)->i_sem);
Hi Chao,
F2FS_I(inode)->i_sem is not needed for this judgment FI_OPENED_FILE area?
because inode_lock has been hold and this is a write lock, if process
A get inode_lock,
other proccesses will be blocked inode_lock until inode_unlock with
FI_OPENED_FILE been set?
how do you think?
thanks！
> + if (opened)
> + goto out_unlock;
> +
> + if (!file_should_truncate(inode))
> + goto out_update;
>
> f2fs_down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> filemap_invalidate_lock(inode->i_mapping);
> @@ -576,16 +581,17 @@ static int finish_preallocate_blocks(struct inode
> *inode)
>
> filemap_invalidate_unlock(inode->i_mapping);
> f2fs_up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> -
> - if (!ret)
> - set_inode_flag(inode, FI_OPENED_FILE);
> -
> - inode_unlock(inode);
> if (ret)
> - return ret;
> + goto out_unlock;
>
> file_dont_truncate(inode);
> - return 0;
> +out_update:
> + f2fs_down_write(&F2FS_I(inode)->i_sem);
> + set_inode_flag(inode, FI_OPENED_FILE);
> + f2fs_up_write(&F2FS_I(inode)->i_sem);
> +out_unlock:
> + inode_unlock(inode);
> + return ret;
> }
>
> static int f2fs_file_open(struct inode *inode, struct file *filp)
> --
> 2.48.1
>
>
>
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