Commit 6304affe authored by Mike Snitzer's avatar Mike Snitzer Committed by Chuck Lever
Browse files

NFSD: Add io_cache_{read,write} controls to debugfs 



Add 'io_cache_read' to NFSD's debugfs interface so that any data
read by NFSD will either be:
- cached using page cache (NFSD_IO_BUFFERED=0)
- cached but removed from the page cache upon completion
  (NFSD_IO_DONTCACHE=1).

io_cache_read may be set by writing to:
  /sys/kernel/debug/nfsd/io_cache_read

Add 'io_cache_write' to NFSD's debugfs interface so that any data
written by NFSD will either be:
- cached using page cache (NFSD_IO_BUFFERED=0)
- cached but removed from the page cache upon completion
  (NFSD_IO_DONTCACHE=1).

io_cache_write may be set by writing to:
  /sys/kernel/debug/nfsd/io_cache_write

The default value for both settings is NFSD_IO_BUFFERED, which is
NFSD's existing behavior for both read and write. Changes to these
settings take immediate effect for all exports and NFS versions.

Currently only xfs and ext4 implement RWF_DONTCACHE. For file
systems that do not implement RWF_DONTCACHE, NFSD use only buffered
I/O when the io_cache setting is NFSD_IO_DONTCACHE.

Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent d6e80d48

fs/nfsd/debugfs.c

+93 −0
Original line number Diff line number Diff line
@@ -27,11 +27,98 @@ static int nfsd_dsr_get(void *data, u64 *val) 
static int nfsd_dsr_set(void *data, u64 val)

{

	nfsd_disable_splice_read = (val > 0);

	if (!nfsd_disable_splice_read) {

		/*

		 * Must use buffered I/O if splice_read is enabled.

		 */

		nfsd_io_cache_read = NFSD_IO_BUFFERED;

	}

	return 0;

}



DEFINE_DEBUGFS_ATTRIBUTE(nfsd_dsr_fops, nfsd_dsr_get, nfsd_dsr_set, "%llu\n");



/*

 * /sys/kernel/debug/nfsd/io_cache_read

 *

 * Contents:

 *   %0: NFS READ will use buffered IO

 *   %1: NFS READ will use dontcache (buffered IO w/ dropbehind)

 *

 * This setting takes immediate effect for all NFS versions,

 * all exports, and in all NFSD net namespaces.

 */



static int nfsd_io_cache_read_get(void *data, u64 *val)

{

	*val = nfsd_io_cache_read;

	return 0;

}



static int nfsd_io_cache_read_set(void *data, u64 val)

{

	int ret = 0;



	switch (val) {

	case NFSD_IO_BUFFERED:

		nfsd_io_cache_read = NFSD_IO_BUFFERED;

		break;

	case NFSD_IO_DONTCACHE:

		/*

		 * Must disable splice_read when enabling

		 * NFSD_IO_DONTCACHE.

		 */

		nfsd_disable_splice_read = true;

		nfsd_io_cache_read = val;

		break;

	default:

		ret = -EINVAL;

		break;

	}



	return ret;

}



DEFINE_DEBUGFS_ATTRIBUTE(nfsd_io_cache_read_fops, nfsd_io_cache_read_get,

			 nfsd_io_cache_read_set, "%llu\n");



/*

 * /sys/kernel/debug/nfsd/io_cache_write

 *

 * Contents:

 *   %0: NFS WRITE will use buffered IO

 *   %1: NFS WRITE will use dontcache (buffered IO w/ dropbehind)

 *

 * This setting takes immediate effect for all NFS versions,

 * all exports, and in all NFSD net namespaces.

 */



static int nfsd_io_cache_write_get(void *data, u64 *val)

{

	*val = nfsd_io_cache_write;

	return 0;

}



static int nfsd_io_cache_write_set(void *data, u64 val)

{

	int ret = 0;



	switch (val) {

	case NFSD_IO_BUFFERED:

	case NFSD_IO_DONTCACHE:

		nfsd_io_cache_write = val;

		break;

	default:

		ret = -EINVAL;

		break;

	}



	return ret;

}



DEFINE_DEBUGFS_ATTRIBUTE(nfsd_io_cache_write_fops, nfsd_io_cache_write_get,

			 nfsd_io_cache_write_set, "%llu\n");



void nfsd_debugfs_exit(void)

{

	debugfs_remove_recursive(nfsd_top_dir);
@@ -44,4 +131,10 @@ void nfsd_debugfs_init(void) 


	debugfs_create_file("disable-splice-read", S_IWUSR | S_IRUGO,

			    nfsd_top_dir, NULL, &nfsd_dsr_fops);



	debugfs_create_file("io_cache_read", 0644, nfsd_top_dir, NULL,

			    &nfsd_io_cache_read_fops);



	debugfs_create_file("io_cache_write", 0644, nfsd_top_dir, NULL,

			    &nfsd_io_cache_write_fops);

}

fs/nfsd/nfsd.h

+9 −0
Original line number Diff line number Diff line
@@ -153,6 +153,15 @@ static inline void nfsd_debugfs_exit(void) {} 


extern bool nfsd_disable_splice_read __read_mostly;



enum {

	/* Any new NFSD_IO enum value must be added at the end */

	NFSD_IO_BUFFERED,

	NFSD_IO_DONTCACHE,

};



extern u64 nfsd_io_cache_read __read_mostly;

extern u64 nfsd_io_cache_write __read_mostly;



extern int nfsd_max_blksize;



static inline int nfsd_v4client(struct svc_rqst *rq)

fs/nfsd/vfs.c

+21 −0
Original line number Diff line number Diff line
@@ -49,6 +49,8 @@ 
#define NFSDDBG_FACILITY		NFSDDBG_FILEOP



bool nfsd_disable_splice_read __read_mostly;

u64 nfsd_io_cache_read __read_mostly = NFSD_IO_BUFFERED;

u64 nfsd_io_cache_write __read_mostly = NFSD_IO_BUFFERED;



/**

 * nfserrno - Map Linux errnos to NFS errnos
@@ -1099,6 +1101,16 @@ __be32 nfsd_iter_read(struct svc_rqst *rqstp, struct svc_fh *fhp, 
	size_t len;



	init_sync_kiocb(&kiocb, file);



	switch (nfsd_io_cache_read) {

	case NFSD_IO_BUFFERED:

		break;

	case NFSD_IO_DONTCACHE:

		if (file->f_op->fop_flags & FOP_DONTCACHE)

			kiocb.ki_flags = IOCB_DONTCACHE;

		break;

	}



	kiocb.ki_pos = offset;



	v = 0;
@@ -1224,6 +1236,15 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, 
	since = READ_ONCE(file->f_wb_err);

	if (verf)

		nfsd_copy_write_verifier(verf, nn);



	switch (nfsd_io_cache_write) {

	case NFSD_IO_BUFFERED:

		break;

	case NFSD_IO_DONTCACHE:

		if (file->f_op->fop_flags & FOP_DONTCACHE)

			kiocb.ki_flags |= IOCB_DONTCACHE;

		break;

	}

	host_err = vfs_iocb_iter_write(file, &kiocb, &iter);

	if (host_err < 0) {

		commit_reset_write_verifier(nn, rqstp, host_err);