On Thu, May 30, 2024 at 10:05 PM Sasha Levin <sashal@xxxxxxxxxx> wrote: > > This is a note to let you know that I've just added the patch titled > > fs: move kiocb_start_write() into vfs_iocb_iter_write() > > to the 6.6-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > The filename of the patch is: > fs-move-kiocb_start_write-into-vfs_iocb_iter_write.patch > and it can be found in the queue-6.6 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable@xxxxxxxxxxxxxxx> know about it. > > > > commit 17f38d69e7960a2b346db04750b0e4ba867c0b83 > Author: Amir Goldstein <amir73il@xxxxxxxxx> > Date: Wed Nov 22 14:27:12 2023 +0200 > > fs: move kiocb_start_write() into vfs_iocb_iter_write() > > [ Upstream commit 6ae654392bb516a0baa47fed1f085d84e8cad739 ] > > 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 comment about semantics change looks like a clue from my past self that backporting this commit as standalone is risky. This commit was part of a pretty big shuffle in splice and ovl code. I'd feel much more comfortable with backporting the entire ovl series 14ab6d425e8067..5b02bfc1e7e3 and splice series v6.7..6ae654392bb51 than just 3 individual commits in the middle. Thanks, Amir. > This is needed for fanotify "pre content" events. > > Suggested-by: Jan Kara <jack@xxxxxxx> > Suggested-by: Josef Bacik <josef@xxxxxxxxxxxxxx> > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> > Link: https://lore.kernel.org/r/20231122122715.2561213-14-amir73il@xxxxxxxxx > Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> > Reviewed-by: Jan Kara <jack@xxxxxxx> > Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> > Stable-dep-of: 7c98f7cb8fda ("remove call_{read,write}_iter() functions") > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > > diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c > index 009d23cd435b5..5857241c59181 100644 > --- a/fs/cachefiles/io.c > +++ b/fs/cachefiles/io.c > @@ -259,7 +259,8 @@ static void cachefiles_write_complete(struct kiocb *iocb, long ret) > > _enter("%ld", ret); > > - kiocb_end_write(iocb); > + if (ki->was_async) > + kiocb_end_write(iocb); > > if (ret < 0) > trace_cachefiles_io_error(object, inode, ret, > @@ -319,8 +320,6 @@ int __cachefiles_write(struct cachefiles_object *object, > ki->iocb.ki_complete = cachefiles_write_complete; > atomic_long_add(ki->b_writing, &cache->b_writing); > > - kiocb_start_write(&ki->iocb); > - > get_file(ki->iocb.ki_filp); > cachefiles_grab_object(object, cachefiles_obj_get_ioreq); > > diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c > index 9fd88579bfbfb..a1c64c2b8e204 100644 > --- a/fs/overlayfs/file.c > +++ b/fs/overlayfs/file.c > @@ -295,10 +295,8 @@ static void ovl_aio_cleanup_handler(struct ovl_aio_req *aio_req) > struct kiocb *iocb = &aio_req->iocb; > struct kiocb *orig_iocb = aio_req->orig_iocb; > > - if (iocb->ki_flags & IOCB_WRITE) { > - kiocb_end_write(iocb); > + if (iocb->ki_flags & IOCB_WRITE) > ovl_file_modified(orig_iocb->ki_filp); > - } > > orig_iocb->ki_pos = iocb->ki_pos; > ovl_aio_put(aio_req); > @@ -310,6 +308,9 @@ static void ovl_aio_rw_complete(struct kiocb *iocb, long res) > struct ovl_aio_req, iocb); > struct kiocb *orig_iocb = aio_req->orig_iocb; > > + if (iocb->ki_flags & IOCB_WRITE) > + kiocb_end_write(iocb); > + > ovl_aio_cleanup_handler(aio_req); > orig_iocb->ki_complete(orig_iocb, res); > } > @@ -421,7 +422,6 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) > aio_req->iocb.ki_flags = ifl; > aio_req->iocb.ki_complete = ovl_aio_rw_complete; > refcount_set(&aio_req->ref, 2); > - kiocb_start_write(&aio_req->iocb); > ret = vfs_iocb_iter_write(real.file, &aio_req->iocb, iter); > ovl_aio_put(aio_req); > if (ret != -EIOCBQUEUED) > diff --git a/fs/read_write.c b/fs/read_write.c > index 4771701c896ba..9a56949f3b8d1 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -865,6 +865,10 @@ static ssize_t do_iter_write(struct file *file, struct iov_iter *iter, > return ret; > } > > +/* > + * Caller is responsible for calling kiocb_end_write() on completion > + * if async iocb was queued. > + */ > ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb, > struct iov_iter *iter) > { > @@ -885,7 +889,10 @@ ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb, > if (ret < 0) > return ret; > > + kiocb_start_write(iocb); > ret = call_write_iter(file, iocb, iter); > + if (ret != -EIOCBQUEUED) > + kiocb_end_write(iocb); > if (ret > 0) > fsnotify_modify(file); >
