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authorChuck Lever <chuck.lever@oracle.com>2023-08-25 15:04:23 -0400
committerChuck Lever <chuck.lever@oracle.com>2023-08-29 17:45:22 -0400
commitb38a6023da6a12b561f0421c6a5a1f7624a1529c (patch)
tree0229892422a6dbfbaf712652771eacea56583895 /Documentation/filesystems/nfs
parent899525e892dd165d2bb2e41f9f9d9d82574b31b5 (diff)
Documentation: Add missing documentation for EXPORT_OP flags
The commits that introduced these flags neglected to update the Documentation/filesystems/nfs/exporting.rst file. Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'Documentation/filesystems/nfs')
-rw-r--r--Documentation/filesystems/nfs/exporting.rst26
1 files changed, 26 insertions, 0 deletions
diff --git a/Documentation/filesystems/nfs/exporting.rst b/Documentation/filesystems/nfs/exporting.rst
index 3d97b8d8f735..4b30daee399a 100644
--- a/Documentation/filesystems/nfs/exporting.rst
+++ b/Documentation/filesystems/nfs/exporting.rst
@@ -215,3 +215,29 @@ following flags are defined:
This flag causes nfsd to close any open files for this inode _before_
calling into the vfs to do an unlink or a rename that would replace
an existing file.
+
+ EXPORT_OP_REMOTE_FS - Backing storage for this filesystem is remote
+ PF_LOCAL_THROTTLE exists for loopback NFSD, where a thread needs to
+ write to one bdi (the final bdi) in order to free up writes queued
+ to another bdi (the client bdi). Such threads get a private balance
+ of dirty pages so that dirty pages for the client bdi do not imact
+ the daemon writing to the final bdi. For filesystems whose durable
+ storage is not local (such as exported NFS filesystems), this
+ constraint has negative consequences. EXPORT_OP_REMOTE_FS enables
+ an export to disable writeback throttling.
+
+ EXPORT_OP_NOATOMIC_ATTR - Filesystem does not update attributes atomically
+ EXPORT_OP_NOATOMIC_ATTR indicates that the exported filesystem
+ cannot provide the semantics required by the "atomic" boolean in
+ NFSv4's change_info4. This boolean indicates to a client whether the
+ returned before and after change attributes were obtained atomically
+ with the respect to the requested metadata operation (UNLINK,
+ OPEN/CREATE, MKDIR, etc).
+
+ EXPORT_OP_FLUSH_ON_CLOSE - Filesystem flushes file data on close(2)
+ On most filesystems, inodes can remain under writeback after the
+ file is closed. NFSD relies on client activity or local flusher
+ threads to handle writeback. Certain filesystems, such as NFS, flush
+ all of an inode's dirty data on last close. Exports that behave this
+ way should set EXPORT_OP_FLUSH_ON_CLOSE so that NFSD knows to skip
+ waiting for writeback when closing such files.