Linus recently made the page lock more fair. That means that the old pattern where we returned from ->readpage with the page unlocked and then attempted to re-lock it will send us to the back of the queue for this page's lock. Ideally all filesystems would return from ->readpage with the page Uptodate and Locked, but it's a bit painful to convert all the asynchronous readpage implementations to synchronous. These ones are already synchronous, so convert them while I work on iomap. A further benefit is that a synchronous readpage implementation allows us to return an error to someone who might actually care about it. There's no need to SetPageError, but I don't want to learn about how a dozen filesystems handle I/O errors (hint: they're all different), so I have not attempted to change that. Please review your filesystem carefully. I've tried to catch all the places where a filesystem calls its own internal readpage implementation without going through ->readpage, but I may have missed some. Matthew Wilcox (Oracle) (13): mm: Add AOP_UPDATED_PAGE return value 9p: Tell the VFS that readpage was synchronous afs: Tell the VFS that readpage was synchronous ceph: Tell the VFS that readpage was synchronous cifs: Tell the VFS that readpage was synchronous cramfs: Tell the VFS that readpage was synchronous ecryptfs: Tell the VFS that readpage was synchronous fuse: Tell the VFS that readpage was synchronous hostfs: Tell the VFS that readpage was synchronous jffs2: Tell the VFS that readpage was synchronous ubifs: Tell the VFS that readpage was synchronous udf: Tell the VFS that readpage was synchronous vboxsf: Tell the VFS that readpage was synchronous Documentation/filesystems/locking.rst | 7 ++++--- Documentation/filesystems/vfs.rst | 21 ++++++++++++++------- fs/9p/vfs_addr.c | 6 +++++- fs/afs/file.c | 3 ++- fs/ceph/addr.c | 9 +++++---- fs/cifs/file.c | 8 ++++++-- fs/cramfs/inode.c | 5 ++--- fs/ecryptfs/mmap.c | 11 ++++++----- fs/fuse/file.c | 2 ++ fs/hostfs/hostfs_kern.c | 2 ++ fs/jffs2/file.c | 6 ++++-- fs/ubifs/file.c | 16 ++++++++++------ fs/udf/file.c | 3 +-- fs/vboxsf/file.c | 2 ++ include/linux/fs.h | 5 +++++ mm/filemap.c | 12 ++++++++++-- 16 files changed, 80 insertions(+), 38 deletions(-) -- 2.28.0
