On Mon, May 16, 2022 at 09:47:09AM -0700, Stefan Roesch wrote:
> This splits off the functions need_file_update_time() and
> do_file_update_time() from the function file_update_time().
>
> This is required to support async buffered writes.
> No intended functional changes in this patch.
>
> Signed-off-by: Stefan Roesch <shr@xxxxxx>
> ---
> fs/inode.c | 71 ++++++++++++++++++++++++++++++++++++------------------
> 1 file changed, 47 insertions(+), 24 deletions(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index a6d70a1983f8..1d0b02763e98 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -2054,35 +2054,22 @@ int file_remove_privs(struct file *file)
> }
> EXPORT_SYMBOL(file_remove_privs);
>
> -/**
> - * file_update_time - update mtime and ctime time
> - * @file: file accessed
> - *
> - * Update the mtime and ctime members of an inode and mark the inode
> - * for writeback. Note that this function is meant exclusively for
> - * usage in the file write path of filesystems, and filesystems may
> - * choose to explicitly ignore update via this function with the
> - * S_NOCMTIME inode flag, e.g. for network filesystem where these
> - * timestamps are handled by the server. This can return an error for
> - * file systems who need to allocate space in order to update an inode.
> - */
> -
> -int file_update_time(struct file *file)
> +static int need_file_update_time(struct inode *inode, struct file *file,
> + struct timespec64 *now)
I think file_need_update_time() is easier to understand.
> {
> - struct inode *inode = file_inode(file);
> - struct timespec64 now;
> int sync_it = 0;
> - int ret;
> +
> + if (unlikely(file->f_mode & FMODE_NOCMTIME))
> + return 0;
Moving this into this generic helper and using the generic helper
directly in file_update_atime() leads to a change in behavior for
file_update_time() callers. Currently they'd get time settings updated
even if FMODE_NOCMTIME is set but with this change they'd not get it
updated anymore if FMODE_NOCMTIME is set. Am I reading this right?
Is this a bugfix? And if so it should be split into a separate commit...
>
> /* First try to exhaust all avenues to not sync */
> if (IS_NOCMTIME(inode))
> return 0;
>
> - now = current_time(inode);
> - if (!timespec64_equal(&inode->i_mtime, &now))
> + if (!timespec64_equal(&inode->i_mtime, now))
> sync_it = S_MTIME;
>
> - if (!timespec64_equal(&inode->i_ctime, &now))
> + if (!timespec64_equal(&inode->i_ctime, now))
> sync_it |= S_CTIME;
>
> if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode))
> @@ -2091,15 +2078,49 @@ int file_update_time(struct file *file)
> if (!sync_it)
> return 0;
>
> + return sync_it;
> +}
> +
> +static int do_file_update_time(struct inode *inode, struct file *file,
> + struct timespec64 *now, int sync_mode)
> +{
> + int ret;
> +
> /* Finally allowed to write? Takes lock. */
> if (__mnt_want_write_file(file))
> return 0;
>
> - ret = inode_update_time(inode, &now, sync_it);
> + ret = inode_update_time(inode, now, sync_mode);
> __mnt_drop_write_file(file);
>
> return ret;
> }
Maybe
static int __file_update_time(struct inode *inode, struct file *file,
struct timespec64 *now, int sync_mode)
{
int ret = 0;
/* try to update time settings */
if (!__mnt_want_write_file(file)) {
ret = inode_update_time(inode, now, sync_mode);
__mnt_drop_write_file(file);
}
return ret;
}
reads a little easier and the old comment is a bit confusing imho. I'd
just say we keep it short.
> +
> +/**
> + * file_update_time - update mtime and ctime time
> + * @file: file accessed
> + *
> + * Update the mtime and ctime members of an inode and mark the inode
> + * for writeback. Note that this function is meant exclusively for
> + * usage in the file write path of filesystems, and filesystems may
> + * choose to explicitly ignore update via this function with the
> + * S_NOCMTIME inode flag, e.g. for network filesystem where these
> + * timestamps are handled by the server. This can return an error for
> + * file systems who need to allocate space in order to update an inode.
> + */
> +
> +int file_update_time(struct file *file)
My same lame complaint as before to make this kernel-doc. :)
/**
* file_update_time - update mtime and ctime time
* @file: file accessed
*
* Update the mtime and ctime members of an inode and mark the inode or
* writeback. Note that this function is meant exclusively for sage in
* the file write path of filesystems, and filesystems may hoose to
* explicitly ignore update via this function with the _NOCMTIME inode
* flag, e.g. for network filesystem where these imestamps are handled
* by the server. This can return an error for ile systems who need to
* allocate space in order to update an inode.
*
* Return: 0 on success, negative errno on failure.
*/
int file_update_time(struct file *file)
> +{
> + int err;
> + struct inode *inode = file_inode(file);
> + struct timespec64 now = current_time(inode);
> +
> + err = need_file_update_time(inode, file, &now);
> + if (err < 0)
> + return err;
I may misread this but shouldn't this be err <= 0, i.e., if it returns 0
then we don't need to update time?
> +
> + return do_file_update_time(inode, file, &now, err);
> +}
> EXPORT_SYMBOL(file_update_time);
>
> /* Caller must hold the file's inode lock */
> @@ -2108,6 +2129,7 @@ int file_modified(struct file *file)
> int ret;
> struct dentry *dentry = file_dentry(file);
> struct inode *inode = file_inode(file);
> + struct timespec64 now = current_time(inode);
>
> /*
> * Clear the security bits if the process is not being run by root.
> @@ -2122,10 +2144,11 @@ int file_modified(struct file *file)
> return ret;
> }
>
> - if (unlikely(file->f_mode & FMODE_NOCMTIME))
> - return 0;
> + ret = need_file_update_time(inode, file, &now);
> + if (ret <= 0)
> + return ret;
>
> - return file_update_time(file);
> + return do_file_update_time(inode, file, &now, ret);
> }
> EXPORT_SYMBOL(file_modified);
>
> --
> 2.30.2
>
