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authorDavid Howells <dhowells@redhat.com>2023-10-12 11:06:24 +0300
committerDavid Howells <dhowells@redhat.com>2023-12-28 12:45:27 +0300
commit41d8e7673a7726cba57cb8112d81c89cfb6c3e35 (patch)
tree1ae96a5d0a483df02adc4f4f1af6c209b3fbc25d /include/linux/netfs.h
parent4a79616cfb27d76947ea37f0336745ef929d56be (diff)
downloadlinux-41d8e7673a7726cba57cb8112d81c89cfb6c3e35.tar.xz
netfs: Implement a write-through caching option
Provide a flag whereby a filesystem may request that cifs_perform_write() perform write-through caching. This involves putting pages directly into writeback rather than dirty and attaching them to a write operation as we go. Further, the writes being made are limited to the byte range being written rather than whole folios being written. This can be used by cifs, for example, to deal with strict byte-range locking. This can't be used with content encryption as that may require expansion of the write RPC beyond the write being made. This doesn't affect writes via mmap - those are written back in the normal way; similarly failed writethrough writes are marked dirty and left to writeback to retry. Another option would be to simply invalidate them, but the contents can be simultaneously accessed by read() and through mmap. Signed-off-by: David Howells <dhowells@redhat.com> cc: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org
Diffstat (limited to 'include/linux/netfs.h')
-rw-r--r--include/linux/netfs.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 29c66acad925..8a2dd882a781 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -139,6 +139,7 @@ struct netfs_inode {
unsigned long flags;
#define NETFS_ICTX_ODIRECT 0 /* The file has DIO in progress */
#define NETFS_ICTX_UNBUFFERED 1 /* I/O should not use the pagecache */
+#define NETFS_ICTX_WRITETHROUGH 2 /* Write-through caching */
};
/*
@@ -227,6 +228,7 @@ enum netfs_io_origin {
NETFS_READPAGE, /* This read is a synchronous read */
NETFS_READ_FOR_WRITE, /* This read is to prepare a write */
NETFS_WRITEBACK, /* This write was triggered by writepages */
+ NETFS_WRITETHROUGH, /* This write was made by netfs_perform_write() */
NETFS_LAUNDER_WRITE, /* This is triggered by ->launder_folio() */
NETFS_UNBUFFERED_WRITE, /* This is an unbuffered write */
NETFS_DIO_READ, /* This is a direct I/O read */