iversion: add a routine to update a raw value with a larger one (441d3676) · Commits · 戴 / test

Under ceph, clients can be independently updating iversion themselves, while working under comprehensive sets of caps on an inode. In that situation we always want to prefer the largest value of a change attribute. Add a new function that will update a raw value with a larger one, but otherwise leave it alone. Signed-off-by:

Jeff Layton <jlayton@kernel.org> Reviewed-by:

"Yan, Zheng" <zyan@redhat.com> Signed-off-by:

Ilya Dryomov <idryomov@gmail.com>

include/linux/iversion.h

+24 −0

Original line number	Diff line number	Diff line
		@@ -112,6 +112,30 @@ inode_peek_iversion_raw(const struct inode *inode)
		return atomic64_read(&inode->i_version);
		}

		/**
		* inode_set_max_iversion_raw - update i_version new value is larger
		* @inode: inode to set
		* @val: new i_version to set
		*
		* Some self-managed filesystems (e.g Ceph) will only update the i_version
		* value if the new value is larger than the one we already have.
		*/
		static inline void
		inode_set_max_iversion_raw(struct inode *inode, u64 val)
		{
		u64 cur, old;

		cur = inode_peek_iversion_raw(inode);
		for (;;) {
		if (cur > val)
		break;
		old = atomic64_cmpxchg(&inode->i_version, cur, val);
		if (likely(old == cur))
		break;
		cur = old;
		}
		}

		/**
		* inode_set_iversion - set i_version to a particular value
		* @inode: inode to set

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