kernel/linux.git/fs/netfs/locking.c, branch v6.12.80

netfs: Downgrade i_rwsem for a buffered write

2024-10-17T13:33:42+00:00

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 Link: https://lore.kernel.org/r/1317958.1729096113@warthog.procyon.org.uk cc: Steve French cc: Paulo Alcantara cc: Trond Myklebust cc: Jeff Layton 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

inode: remove __I_DIO_WAKEUP

2024-08-30T06:22:37+00:00

Afaict, we can just rely on inode->i_dio_count for waiting instead of this awkward indirection through __I_DIO_WAKEUP. This survives LTP dio and xfstests dio tests. Link: https://lore.kernel.org/r/20240816-vfs-misc-dio-v1-1-80fe21a2c710@kernel.org Reviewed-by: Josef Bacik Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner

netfs: Implement unbuffered/DIO vs buffered I/O locking

2023-12-24T15:08:52+00:00

Borrow NFS's direct-vs-buffered I/O locking into netfslib. Similar code is also used in ceph. Modify it to have the correct checker annotations for i_rwsem lock acquisition/release and to return -ERESTARTSYS if waits are interrupted. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org