fs: move kiocb_start_write() into vfs_iocb_iter_write()
In vfs code, sb_start_write() is usually called after the permission hook in rw_verify_area(). vfs_iocb_iter_write() is an exception to this rule, where kiocb_start_write() is called by its callers. Move kiocb_start_write() from the callers into vfs_iocb_iter_write() after the rw_verify_area() checks, to make them "start-write-safe". The semantics of vfs_iocb_iter_write() is changed, so that the caller is responsible for calling kiocb_end_write() on completion only if async iocb was queued. The completion handlers of both callers were adapted to this semantic change. This is needed for fanotify "pre content" events. Suggested-by: Jan Kara <jack@suse.cz> Suggested-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Link: https://lore.kernel.org/r/20231122122715.2561213-14-amir73il@gmail.com Reviewed-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Christian Brauner <brauner@kernel.org>
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3 changed files with 13 additions and 7 deletions
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@ -259,7 +259,8 @@ static void cachefiles_write_complete(struct kiocb *iocb, long ret)
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_enter("%ld", ret);
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_enter("%ld", ret);
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kiocb_end_write(iocb);
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if (ki->was_async)
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kiocb_end_write(iocb);
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if (ret < 0)
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if (ret < 0)
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trace_cachefiles_io_error(object, inode, ret,
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trace_cachefiles_io_error(object, inode, ret,
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@ -319,8 +320,6 @@ int __cachefiles_write(struct cachefiles_object *object,
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ki->iocb.ki_complete = cachefiles_write_complete;
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ki->iocb.ki_complete = cachefiles_write_complete;
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atomic_long_add(ki->b_writing, &cache->b_writing);
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atomic_long_add(ki->b_writing, &cache->b_writing);
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kiocb_start_write(&ki->iocb);
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get_file(ki->iocb.ki_filp);
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get_file(ki->iocb.ki_filp);
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cachefiles_grab_object(object, cachefiles_obj_get_ioreq);
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cachefiles_grab_object(object, cachefiles_obj_get_ioreq);
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@ -295,10 +295,8 @@ static void ovl_aio_cleanup_handler(struct ovl_aio_req *aio_req)
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struct kiocb *iocb = &aio_req->iocb;
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struct kiocb *iocb = &aio_req->iocb;
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struct kiocb *orig_iocb = aio_req->orig_iocb;
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struct kiocb *orig_iocb = aio_req->orig_iocb;
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if (iocb->ki_flags & IOCB_WRITE) {
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if (iocb->ki_flags & IOCB_WRITE)
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kiocb_end_write(iocb);
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ovl_file_modified(orig_iocb->ki_filp);
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ovl_file_modified(orig_iocb->ki_filp);
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}
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orig_iocb->ki_pos = iocb->ki_pos;
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orig_iocb->ki_pos = iocb->ki_pos;
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ovl_aio_put(aio_req);
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ovl_aio_put(aio_req);
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@ -310,6 +308,9 @@ static void ovl_aio_rw_complete(struct kiocb *iocb, long res)
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struct ovl_aio_req, iocb);
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struct ovl_aio_req, iocb);
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struct kiocb *orig_iocb = aio_req->orig_iocb;
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struct kiocb *orig_iocb = aio_req->orig_iocb;
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if (iocb->ki_flags & IOCB_WRITE)
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kiocb_end_write(iocb);
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ovl_aio_cleanup_handler(aio_req);
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ovl_aio_cleanup_handler(aio_req);
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orig_iocb->ki_complete(orig_iocb, res);
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orig_iocb->ki_complete(orig_iocb, res);
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}
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}
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@ -456,7 +457,6 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
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aio_req->iocb.ki_flags = ifl;
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aio_req->iocb.ki_flags = ifl;
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aio_req->iocb.ki_complete = ovl_aio_queue_completion;
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aio_req->iocb.ki_complete = ovl_aio_queue_completion;
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refcount_set(&aio_req->ref, 2);
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refcount_set(&aio_req->ref, 2);
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kiocb_start_write(&aio_req->iocb);
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ret = vfs_iocb_iter_write(real.file, &aio_req->iocb, iter);
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ret = vfs_iocb_iter_write(real.file, &aio_req->iocb, iter);
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ovl_aio_put(aio_req);
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ovl_aio_put(aio_req);
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if (ret != -EIOCBQUEUED)
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if (ret != -EIOCBQUEUED)
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@ -829,6 +829,10 @@ out:
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}
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}
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EXPORT_SYMBOL(vfs_iter_read);
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EXPORT_SYMBOL(vfs_iter_read);
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/*
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* Caller is responsible for calling kiocb_end_write() on completion
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* if async iocb was queued.
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*/
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ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb,
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ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb,
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struct iov_iter *iter)
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struct iov_iter *iter)
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{
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{
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@ -849,7 +853,10 @@ ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb,
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if (ret < 0)
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if (ret < 0)
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return ret;
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return ret;
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kiocb_start_write(iocb);
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ret = call_write_iter(file, iocb, iter);
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ret = call_write_iter(file, iocb, iter);
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if (ret != -EIOCBQUEUED)
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kiocb_end_write(iocb);
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if (ret > 0)
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if (ret > 0)
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fsnotify_modify(file);
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fsnotify_modify(file);
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