Re: [PATCH 07/17] vfs: Introduce new helpers for syncing after writing to O_SYNC file or IS_SYNC inode

From: Jamie Lokier
Date: Sun Aug 30 2009 - 12:37:14 EST

Christoph Hellwig wrote:
> int generic_write_sync(struct file *file, loff_t pos, loff_t count)
> {
> if (!(file->f_flags & O_SYNC) && !IS_SYNC(file->f_mapping->host))
> return 0;
> return vfs_fsync_range(file, file->f_path.dentry, pos,
> pos + count - 1, 1);
> }
> and we can look into replacing the datasync flag with something more
> meaningfull later through the whole fsync stack.

I like that. It looks really clear and self-documenting, if
vfs_fsync_range does what it sounds like, which is a nice change.

If I've guessed right what that code does, proper O_RSYNC will be easy:

int generic_sync_before_read(struct file *file, loff_t pos, loff_t count)
int is_sync = ((file->f_flags & O_SYNC)
|| IS_SYNC(file->f_mapping->host));
int is_dsync = is_sync || (file->f_flags & O_DSYNC);

if (!is_dsync || !(file->f_flags & O_RSYNC))
return 0;
return vfs_fsync_range(file, file->f_ath.denty, pos,
pos + count - 1, is_sync);

(By the way, did I mention Irix has range-fsync and range-fdatasync
system calls too :-) (actually fcntls))

-- Jamie
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