Add support for FOPEN_NOFLUSH flag

Allow requesting from kernel to avoid flush on close at file open
time.  If kernel does not support FOPEN_NOFLUSH flag, the request
will be ignored.

For passthrough_hp example, request to avoid flush on close when
writeback cache is disabled and file is opened O_RDONLY.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>

diff --git a/ChangeLog.rst b/ChangeLog.rst
index 521c163feb4e65b4763f669bd1ce3aa1de4788a8..96f4fb7af5ddba647799aac18264f0777413fd87 100644 (file)
--- a/ChangeLog.rst
+++ b/ChangeLog.rst
@@ -1,3 +1,8 @@
+Unreleased Changes
+==================
+
+* Add support for flag FOPEN_NOFLUSH for avoiding flush on close.
+
 libfuse 3.10.5 (2021-09-06)
 ===========================
 

diff --git a/example/passthrough_hp.cc b/example/passthrough_hp.cc
index 872fc731121be0f9a65abccdbeff80dcc58c2376..e15f893608868743257f3472e3f2ee3752ba1781 100644 (file)
--- a/example/passthrough_hp.cc
+++ b/example/passthrough_hp.cc
@@ -856,6 +856,7 @@ static void sfs_open(fuse_req_t req, fuse_ino_t ino, fuse_file_info *fi) {
     lock_guard<mutex> g {inode.m};
     inode.nopen++;
     fi->keep_cache = (fs.timeout != 0);
+    fi->noflush = (fs.timeout == 0 && (fi->flags & O_ACCMODE) == O_RDONLY);
     fi->fh = fd;
     fuse_reply_open(req, fi);
 }

diff --git a/include/fuse_common.h b/include/fuse_common.h
index ea4bdb02427d244c24dd87519ca3883e4a659f75..d7481befdfa4cb7c9d75131e3d936a490dc9d456 100644 (file)
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -83,8 +83,12 @@ struct fuse_file_info {
            nothing when set by open()). */
        unsigned int cache_readdir : 1;
 
+       /** Can be filled in by open, to indicate that flush is not needed
+           on close. */
+       unsigned int noflush : 1;
+
        /** Padding.  Reserved for future use*/
-       unsigned int padding : 25;
+       unsigned int padding : 24;
        unsigned int padding2 : 32;
 
        /** File handle id.  May be filled in by filesystem in create,

diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 018a00a2da0ff502ab043bc2f62e1025915c4129..48f2000b18b75d8a19b06991cbb9c65ac9a0d020 100644 (file)
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -238,12 +238,14 @@ struct fuse_file_lock {
  * FOPEN_NONSEEKABLE: the file is not seekable
  * FOPEN_CACHE_DIR: allow caching this directory
  * FOPEN_STREAM: the file is stream-like (no file position at all)
+ * FOPEN_NOFLUSH: don't flush data cache on close (unless FUSE_WRITEBACK_CACHE)
  */
 #define FOPEN_DIRECT_IO                (1 << 0)
 #define FOPEN_KEEP_CACHE       (1 << 1)
 #define FOPEN_NONSEEKABLE      (1 << 2)
 #define FOPEN_CACHE_DIR                (1 << 3)
 #define FOPEN_STREAM           (1 << 4)
+#define FOPEN_NOFLUSH          (1 << 5)
 
 /**
  * INIT request/reply flags

diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index d227688b2d9aa8abc9c2f68c78d57540a67640a0..b5638fc504e11c10954c48f93cd91893edb9d567 100644 (file)
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -395,6 +395,8 @@ static void fill_open(struct fuse_open_out *arg,
                arg->open_flags |= FOPEN_CACHE_DIR;
        if (f->nonseekable)
                arg->open_flags |= FOPEN_NONSEEKABLE;
+       if (f->noflush)
+               arg->open_flags |= FOPEN_NOFLUSH;
 }
 
 int fuse_reply_entry(fuse_req_t req, const struct fuse_entry_param *e)