Re: [PATCH 2/9] vfs: export do_splice_direct() to modules

[David Howells]

Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:

> fs/cachefiles/rdwr.c:967:                       ret = file->f_op->write(
> 
> cachefiles_write_page(); no fucking idea what locks might be held by caller
> and potentially that's a rather nasty source of PITA

The caller of cachefiles_write_page() (ie. fscache_write_op()) holds no locks
over the call.

__fscache_write_page() queues the pages for writing to the cache from the
netfs's read-side routines and returns immediately.

fscache_write_op() then picks them up in the background and passes them over
to the backend (eg. cachefiles_write_page()) which writes them out to the
cache.

So I think it should be safe to call file_start/end_write() or whatever around
the file->f_op->write() calls.

David
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