Commit 02c048b9 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

fuse: allow batching of FORGET requests 



Terje Malmedal reports that a fuse filesystem with 32 million inodes
on a machine with lots of memory can take up to 30 minutes to process
FORGET requests when all those inodes are evicted from the icache.

To solve this, create a BATCH_FORGET request that allows up to about
8000 FORGET requests to be sent in a single message.

This request is only sent if userspace supports interface version 7.16
or later, otherwise fall back to sending individual FORGET messages.

Reported-by: default avatarTerje Malmedal <terje.malmedal@usit.uio.no>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
parent 07e77dca

fs/fuse/dev.c

+81 −11
Original line number Diff line number Diff line
@@ -254,8 +254,8 @@ static void queue_request(struct fuse_conn *fc, struct fuse_req *req) 
void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,

		       u64 nodeid, u64 nlookup)

{

	forget->nodeid = nodeid;

	forget->nlookup = nlookup;

	forget->forget_one.nodeid = nodeid;

	forget->forget_one.nlookup = nlookup;



	spin_lock(&fc->lock);

	fc->forget_list_tail->next = forget;
@@ -974,15 +974,26 @@ __releases(fc->lock) 
	return err ? err : reqsize;

}



static struct fuse_forget_link *dequeue_forget(struct fuse_conn *fc)

static struct fuse_forget_link *dequeue_forget(struct fuse_conn *fc,

					       unsigned max,

					       unsigned *countp)

{

	struct fuse_forget_link *forget = fc->forget_list_head.next;

	struct fuse_forget_link *head = fc->forget_list_head.next;

	struct fuse_forget_link **newhead = &head;

	unsigned count;



	fc->forget_list_head.next = forget->next;

	for (count = 0; *newhead != NULL && count < max; count++)

		newhead = &(*newhead)->next;



	fc->forget_list_head.next = *newhead;

	*newhead = NULL;

	if (fc->forget_list_head.next == NULL)

		fc->forget_list_tail = &fc->forget_list_head;



	return forget;

	if (countp != NULL)

		*countp = count;



	return head;

}



static int fuse_read_single_forget(struct fuse_conn *fc,
@@ -991,13 +1002,13 @@ static int fuse_read_single_forget(struct fuse_conn *fc, 
__releases(fc->lock)

{

	int err;

	struct fuse_forget_link *forget = dequeue_forget(fc);

	struct fuse_forget_link *forget = dequeue_forget(fc, 1, NULL);

	struct fuse_forget_in arg = {

		.nlookup = forget->nlookup,

		.nlookup = forget->forget_one.nlookup,

	};

	struct fuse_in_header ih = {

		.opcode = FUSE_FORGET,

		.nodeid = forget->nodeid,

		.nodeid = forget->forget_one.nodeid,

		.unique = fuse_get_unique(fc),

		.len = sizeof(ih) + sizeof(arg),

	};
@@ -1018,6 +1029,65 @@ __releases(fc->lock) 
	return ih.len;

}



static int fuse_read_batch_forget(struct fuse_conn *fc,

				   struct fuse_copy_state *cs, size_t nbytes)

__releases(fc->lock)

{

	int err;

	unsigned max_forgets;

	unsigned count;

	struct fuse_forget_link *head;

	struct fuse_batch_forget_in arg = { .count = 0 };

	struct fuse_in_header ih = {

		.opcode = FUSE_BATCH_FORGET,

		.unique = fuse_get_unique(fc),

		.len = sizeof(ih) + sizeof(arg),

	};



	if (nbytes < ih.len) {

		spin_unlock(&fc->lock);

		return -EINVAL;

	}



	max_forgets = (nbytes - ih.len) / sizeof(struct fuse_forget_one);

	head = dequeue_forget(fc, max_forgets, &count);

	spin_unlock(&fc->lock);



	arg.count = count;

	ih.len += count * sizeof(struct fuse_forget_one);

	err = fuse_copy_one(cs, &ih, sizeof(ih));

	if (!err)

		err = fuse_copy_one(cs, &arg, sizeof(arg));



	while (head) {

		struct fuse_forget_link *forget = head;



		if (!err) {

			err = fuse_copy_one(cs, &forget->forget_one,

					    sizeof(forget->forget_one));

		}

		head = forget->next;

		kfree(forget);

	}



	fuse_copy_finish(cs);



	if (err)

		return err;



	return ih.len;

}



static int fuse_read_forget(struct fuse_conn *fc, struct fuse_copy_state *cs,

			    size_t nbytes)

__releases(fc->lock)

{

	if (fc->minor < 16 || fc->forget_list_head.next->next == NULL)

		return fuse_read_single_forget(fc, cs, nbytes);

	else

		return fuse_read_batch_forget(fc, cs, nbytes);

}



/*

 * Read a single request into the userspace filesystem's buffer.  This

 * function waits until a request is available, then removes it from
@@ -1058,7 +1128,7 @@ static ssize_t fuse_dev_do_read(struct fuse_conn *fc, struct file *file, 


	if (forget_pending(fc)) {

		if (list_empty(&fc->pending) || fc->forget_batch-- > 0)

			return fuse_read_single_forget(fc, cs, nbytes);

			return fuse_read_forget(fc, cs, nbytes);



		if (fc->forget_batch <= -8)

			fc->forget_batch = 16;
@@ -1837,7 +1907,7 @@ __acquires(fc->lock) 
	end_requests(fc, &fc->pending);

	end_requests(fc, &fc->processing);

	while (forget_pending(fc))

		kfree(dequeue_forget(fc));

		kfree(dequeue_forget(fc, 1, NULL));

}



/*

fs/fuse/fuse_i.h

+1 −2
Original line number Diff line number Diff line
@@ -55,8 +55,7 @@ extern unsigned max_user_congthresh; 


/* One forget request */

struct fuse_forget_link {

	u64	nodeid;

	u64	nlookup;

	struct fuse_forget_one forget_one;

	struct fuse_forget_link *next;

};

include/linux/fuse.h

+15 −1
Original line number Diff line number Diff line
@@ -41,6 +41,9 @@ 
 * 7.15

 *  - add store notify

 *  - add retrieve notify

 *

 * 7.16

 *  - add BATCH_FORGET request

 */



#ifndef _LINUX_FUSE_H
@@ -72,7 +75,7 @@ 
#define FUSE_KERNEL_VERSION 7



/** Minor version number of this interface */

#define FUSE_KERNEL_MINOR_VERSION 15

#define FUSE_KERNEL_MINOR_VERSION 16



/** The node ID of the root inode */

#define FUSE_ROOT_ID 1
@@ -256,6 +259,7 @@ enum fuse_opcode { 
	FUSE_IOCTL         = 39,

	FUSE_POLL          = 40,

	FUSE_NOTIFY_REPLY  = 41,

	FUSE_BATCH_FORGET  = 42,



	/* CUSE specific operations */

	CUSE_INIT          = 4096,
@@ -290,6 +294,16 @@ struct fuse_forget_in { 
	__u64	nlookup;

};



struct fuse_forget_one {

	__u64	nodeid;

	__u64	nlookup;

};



struct fuse_batch_forget_in {

	__u32	count;

	__u32	dummy;

};



struct fuse_getattr_in {

	__u32	getattr_flags;

	__u32	dummy;

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