NFS: Use information about the change attribute to optimise updates (6f9be83d) · Commits · EulixOS / Software / Kernel

fs/nfs/inode.c

+93 −18

Original line number	Diff line number	Diff line
		@@ -1657,25 +1657,20 @@ EXPORT_SYMBOL_GPL(_nfs_display_fhandle);
		#endif

		/**
		* nfs_inode_attrs_need_update - check if the inode attributes need updating
		* @inode: pointer to inode
		* nfs_inode_attrs_cmp_generic - compare attributes
		* @fattr: attributes
		* @inode: pointer to inode
		*
		* Attempt to divine whether or not an RPC call reply carrying stale
		* attributes got scheduled after another call carrying updated ones.
		*
		* To do so, the function first assumes that a more recent ctime means
		* that the attributes in fattr are newer, however it also attempt to
		* catch the case where ctime either didn't change, or went backwards
		* (if someone reset the clock on the server) by looking at whether
		* or not this RPC call was started after the inode was last updated.
		* Note also the check for wraparound of 'attr_gencount'
		*
		* The function returns 'true' if it thinks the attributes in 'fattr' are
		* more recent than the ones cached in the inode.
		*
		* The function returns '1' if it thinks the attributes in @fattr are
		* more recent than the ones cached in @inode. Otherwise it returns
		* the value '0'.
		*/
		static int nfs_inode_attrs_need_update(const struct inode inode, const struct nfs_fattr fattr)
		static int nfs_inode_attrs_cmp_generic(const struct nfs_fattr *fattr,
		const struct inode *inode)
		{
		unsigned long attr_gencount = NFS_I(inode)->attr_gencount;

		@@ -1683,15 +1678,93 @@ static int nfs_inode_attrs_need_update(const struct inode *inode, const struct n
		(long)(attr_gencount - nfs_read_attr_generation_counter()) > 0;
		}

		static int nfs_refresh_inode_locked(struct inode inode, struct nfs_fattr fattr)
		/**
		* nfs_inode_attrs_cmp_monotonic - compare attributes
		* @fattr: attributes
		* @inode: pointer to inode
		*
		* Attempt to divine whether or not an RPC call reply carrying stale
		* attributes got scheduled after another call carrying updated ones.
		*
		* We assume that the server observes monotonic semantics for
		* the change attribute, so a larger value means that the attributes in
		* @fattr are more recent, in which case the function returns the
		* value '1'.
		* A return value of '0' indicates no measurable change
		* A return value of '-1' means that the attributes in @inode are
		* more recent.
		*/
		static int nfs_inode_attrs_cmp_monotonic(const struct nfs_fattr *fattr,
		const struct inode *inode)
		{
		int ret;
		s64 diff = fattr->change_attr - inode_peek_iversion_raw(inode);
		if (diff > 0)
		return 1;
		return diff == 0 ? 0 : -1;
		}

		/**
		* nfs_inode_attrs_cmp_strict_monotonic - compare attributes
		* @fattr: attributes
		* @inode: pointer to inode
		*
		* Attempt to divine whether or not an RPC call reply carrying stale
		* attributes got scheduled after another call carrying updated ones.
		*
		* We assume that the server observes strictly monotonic semantics for
		* the change attribute, so a larger value means that the attributes in
		* @fattr are more recent, in which case the function returns the
		* value '1'.
		* A return value of '-1' means that the attributes in @inode are
		* more recent or unchanged.
		*/
		static int nfs_inode_attrs_cmp_strict_monotonic(const struct nfs_fattr *fattr,
		const struct inode *inode)
		{
		return nfs_inode_attrs_cmp_monotonic(fattr, inode) > 0 ? 1 : -1;
		}

		/**
		* nfs_inode_attrs_cmp - compare attributes
		* @fattr: attributes
		* @inode: pointer to inode
		*
		* This function returns '1' if it thinks the attributes in @fattr are
		* more recent than the ones cached in @inode. It returns '-1' if
		* the attributes in @inode are more recent than the ones in @fattr,
		* and it returns 0 if not sure.
		*/
		static int nfs_inode_attrs_cmp(const struct nfs_fattr *fattr,
		const struct inode *inode)
		{
		if (nfs_inode_attrs_cmp_generic(fattr, inode) > 0)
		return 1;
		switch (NFS_SERVER(inode)->change_attr_type) {
		case NFS4_CHANGE_TYPE_IS_UNDEFINED:
		break;
		case NFS4_CHANGE_TYPE_IS_TIME_METADATA:
		if (!(fattr->valid & NFS_ATTR_FATTR_CHANGE))
		break;
		return nfs_inode_attrs_cmp_monotonic(fattr, inode);
		default:
		if (!(fattr->valid & NFS_ATTR_FATTR_CHANGE))
		break;
		return nfs_inode_attrs_cmp_strict_monotonic(fattr, inode);
		}
		return 0;
		}

		static int nfs_refresh_inode_locked(struct inode *inode,
		struct nfs_fattr *fattr)
		{
		int attr_cmp = nfs_inode_attrs_cmp(fattr, inode);
		int ret = 0;

		trace_nfs_refresh_inode_enter(inode);

		if (nfs_inode_attrs_need_update(inode, fattr))
		if (attr_cmp > 0)
		ret = nfs_update_inode(inode, fattr);
		else
		else if (attr_cmp == 0)
		ret = nfs_check_inode_attributes(inode, fattr);

		trace_nfs_refresh_inode_exit(inode, ret);
		@@ -1776,11 +1849,13 @@ EXPORT_SYMBOL_GPL(nfs_post_op_update_inode);
		*/
		int nfs_post_op_update_inode_force_wcc_locked(struct inode inode, struct nfs_fattr fattr)
		{
		int attr_cmp = nfs_inode_attrs_cmp(fattr, inode);
		int status;

		/* Don't do a WCC update if these attributes are already stale */
		if ((fattr->valid & NFS_ATTR_FATTR) == 0 \|\|
		!nfs_inode_attrs_need_update(inode, fattr)) {
		if (attr_cmp < 0)
		return 0;
		if ((fattr->valid & NFS_ATTR_FATTR) == 0 \|\| !attr_cmp) {
		fattr->valid &= ~(NFS_ATTR_FATTR_PRECHANGE
		\| NFS_ATTR_FATTR_PRESIZE
		\| NFS_ATTR_FATTR_PREMTIME

fs/nfs/nfs4proc.c

+17 −3

Original line number	Diff line number	Diff line
		@@ -1186,10 +1186,23 @@ nfs4_update_changeattr_locked(struct inode *inode,
		unsigned long timestamp, unsigned long cache_validity)
		{
		struct nfs_inode *nfsi = NFS_I(inode);
		u64 change_attr = inode_peek_iversion_raw(inode);

		cache_validity \|= NFS_INO_INVALID_CTIME \| NFS_INO_INVALID_MTIME;

		if (cinfo->atomic && cinfo->before == inode_peek_iversion_raw(inode)) {
		switch (NFS_SERVER(inode)->change_attr_type) {
		case NFS4_CHANGE_TYPE_IS_UNDEFINED:
		break;
		case NFS4_CHANGE_TYPE_IS_TIME_METADATA:
		if ((s64)(change_attr - cinfo->after) > 0)
		goto out;
		break;
		default:
		if ((s64)(change_attr - cinfo->after) >= 0)
		goto out;
		}

		if (cinfo->atomic && cinfo->before == change_attr) {
		nfsi->attrtimeo_timestamp = jiffies;
		} else {
		if (S_ISDIR(inode->i_mode)) {
		@@ -1201,7 +1214,7 @@ nfs4_update_changeattr_locked(struct inode *inode,
		cache_validity \|= NFS_INO_REVAL_PAGECACHE;
		}

		if (cinfo->before != inode_peek_iversion_raw(inode))
		if (cinfo->before != change_attr)
		cache_validity \|= NFS_INO_INVALID_ACCESS \|
		NFS_INO_INVALID_ACL \|
		NFS_INO_INVALID_XATTR;
		@@ -1209,8 +1222,9 @@ nfs4_update_changeattr_locked(struct inode *inode,
		inode_set_iversion_raw(inode, cinfo->after);
		nfsi->read_cache_jiffies = timestamp;
		nfsi->attr_gencount = nfs_inc_attr_generation_counter();
		nfs_set_cache_invalid(inode, cache_validity);
		nfsi->cache_validity &= ~NFS_INO_INVALID_CHANGE;
		out:
		nfs_set_cache_invalid(inode, cache_validity);
		}

		void