mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-01-09 14:50:19 +00:00
d6a77668a7
In the I/O locking code borrowed from NFS into netfslib, i_rwsem is held locked across a buffered write - but this causes a performance regression in cifs as it excludes buffered reads for the duration (cifs didn't use any locking for buffered reads). Mitigate this somewhat by downgrading the i_rwsem to a read lock across the buffered write. This at least allows parallel reads to occur whilst excluding other writes, DIO, truncate and setattr. Note that this shouldn't be a problem for a buffered write as a read through an mmap can circumvent i_rwsem anyway. Also note that we might want to make this change in NFS also. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/1317958.1729096113@warthog.procyon.org.uk cc: Steve French <sfrench@samba.org> cc: Paulo Alcantara <pc@manguebit.com> cc: Trond Myklebust <trondmy@kernel.org> cc: Jeff Layton <jlayton@kernel.org> cc: netfs@lists.linux.dev cc: linux-cifs@vger.kernel.org cc: linux-nfs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>