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Commit 3b3be88d authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Use cond_resched_lock() to reduce latencies in the commit scans 



Ensure that we conditionally drop the inode->i_lock when it is safe
to do so in the commit loops.
We do so after locking the nfs_page, but before removing it from the
commit list. We can then use list_safe_reset_next to recover the loop
after the lock is retaken.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 5ae67c4f

fs/nfs/nfs4filelayout.c

+8 −3
Original line number Diff line number Diff line
@@ -936,7 +936,8 @@ static struct pnfs_layout_segment *find_only_write_lseg(struct inode *inode) 
}



static int

filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max)

filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max,

		spinlock_t *lock)

{

	struct list_head *src = &bucket->written;

	struct list_head *dst = &bucket->committing;
@@ -946,6 +947,8 @@ filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max) 
	list_for_each_entry_safe(req, tmp, src, wb_list) {

		if (!nfs_lock_request(req))

			continue;

		if (cond_resched_lock(lock))

			list_safe_reset_next(req, tmp, wb_list);

		nfs_request_remove_commit_list(req);

		clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);

		nfs_list_add_request(req, dst);
@@ -959,7 +962,8 @@ filelayout_scan_ds_commit_list(struct nfs4_fl_commit_bucket *bucket, int max) 
/* Move reqs from written to committing lists, returning count of number moved.

 * Note called with i_lock held.

 */

static int filelayout_scan_commit_lists(struct inode *inode, int max)

static int filelayout_scan_commit_lists(struct inode *inode, int max,

		spinlock_t *lock)

{

	struct pnfs_layout_segment *lseg;

	struct nfs4_filelayout_segment *fl;
@@ -972,7 +976,8 @@ static int filelayout_scan_commit_lists(struct inode *inode, int max) 
	if (fl->commit_through_mds)

		goto out_done;

	for (i = 0; i < fl->number_of_buckets && max != 0; i++) {

		cnt = filelayout_scan_ds_commit_list(&fl->commit_buckets[i], max);

		cnt = filelayout_scan_ds_commit_list(&fl->commit_buckets[i],

				max, lock);

		max -= cnt;

		rv += cnt;

	}

fs/nfs/pnfs.h

+4 −4
Original line number Diff line number Diff line
@@ -97,7 +97,7 @@ struct pnfs_layoutdriver_type { 
	void (*mark_request_commit) (struct nfs_page *req,

					struct pnfs_layout_segment *lseg);

	void (*clear_request_commit) (struct nfs_page *req);

	int (*scan_commit_lists) (struct inode *inode, int max);

	int (*scan_commit_lists) (struct inode *inode, int max, spinlock_t *lock);

	int (*commit_pagelist)(struct inode *inode, struct list_head *mds_pages, int how);



	/*
@@ -294,14 +294,14 @@ pnfs_clear_request_commit(struct nfs_page *req) 
}



static inline int

pnfs_scan_commit_lists(struct inode *inode, int max)

pnfs_scan_commit_lists(struct inode *inode, int max, spinlock_t *lock)

{

	struct pnfs_layoutdriver_type *ld = NFS_SERVER(inode)->pnfs_curr_ld;

	int ret;



	if (ld == NULL || ld->scan_commit_lists == NULL)

		return 0;

	ret = ld->scan_commit_lists(inode, max);

	ret = ld->scan_commit_lists(inode, max, lock);

	if (ret != 0)

		set_bit(NFS_INO_PNFS_COMMIT, &NFS_I(inode)->flags);

	return ret;
@@ -419,7 +419,7 @@ pnfs_clear_request_commit(struct nfs_page *req) 
}



static inline int

pnfs_scan_commit_lists(struct inode *inode, int max)

pnfs_scan_commit_lists(struct inode *inode, int max, spinlock_t *lock)

{

	return 0;

}

fs/nfs/write.c

+8 −3
Original line number Diff line number Diff line
@@ -561,7 +561,8 @@ nfs_need_commit(struct nfs_inode *nfsi) 


/* i_lock held by caller */

static int

nfs_scan_commit_list(struct list_head *src, struct list_head *dst, int max)

nfs_scan_commit_list(struct list_head *src, struct list_head *dst, int max,

		spinlock_t *lock)

{

	struct nfs_page *req, *tmp;

	int ret = 0;
@@ -569,6 +570,8 @@ nfs_scan_commit_list(struct list_head *src, struct list_head *dst, int max) 
	list_for_each_entry_safe(req, tmp, src, wb_list) {

		if (!nfs_lock_request(req))

			continue;

		if (cond_resched_lock(lock))

			list_safe_reset_next(req, tmp, wb_list);

		nfs_request_remove_commit_list(req);

		nfs_list_add_request(req, dst);

		ret++;
@@ -596,8 +599,10 @@ nfs_scan_commit(struct inode *inode, struct list_head *dst) 
	if (nfsi->ncommit > 0) {

		const int max = INT_MAX;



		ret = nfs_scan_commit_list(&nfsi->commit_list, dst, max);

		ret += pnfs_scan_commit_lists(inode, max - ret);

		ret = nfs_scan_commit_list(&nfsi->commit_list, dst, max,

				&inode->i_lock);

		ret += pnfs_scan_commit_lists(inode, max - ret,

				&inode->i_lock);

	}

	spin_unlock(&inode->i_lock);

	return ret;