On Sun, May 26, 2019 at 06:11:34PM +0900, J. R. Okajima wrote: > commit 1e83f8634c6efe7dd4e6036ee202ca10bdbca0b3 > Author: J. R. Okajima <hooanon05g@xxxxxxxxx> > Date: Sat May 25 18:35:13 2019 +0900 > > concrete /proc/mounts > > When the size of /proc/mounts exceeds PAGE_SIZE, seq_read() has to > release namespace_sem via mounts_op.m_stop(). It means if someone else > issues mount(2) or umount(2) and the mounts list got changed, then the > continuous getmntent(3) calls show the incomplete mounts list and some > entries may not appear in it. > > This patch generates the full mounts list when mounts_op.m_start() is > called, and keep it in the seq_file buffer until the file is closed. > The size of the buffer increases if necessary. Other operations m_next, > m_stop, m_show become meaningless, but still necessary for the seq_file > manner. > > I don't think the size of the buffer matters because many /proc entries > already keep the similar PAGE_SIZE buffer. Increasing /proc/mounts > buffer is to keep the correctness of the mount list. > > Reported-by: Kirill Kolyshkin <kolyshkin@xxxxxxxxx> > See-also: https://github.com/kolyshkin/procfs-test > Signed-off-by: J. R. Okajima <hooanon05g@xxxxxxxxx> Translation: let's generate the entire contents on the first read() and keep it until the sucker's closed; that way userland wont' see anything changing under it. Oh, wait... NAK.
