[PATCH 13/16] iversion: add a routine to update a raw value with a larger one

Machines can be independently updating iversion themselves, while working under comprehensive sets of caps on an inode. Add a new function that will update a raw value with a larger one. Signed-off-by: Jeff Layton <jlayton(a)kernel.org> --- include/linux/iversion.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/include/linux/iversion.h b/include/linux/iversion.h index be50ef7cedab..2917ef990d43 100644 --- a/include/linux/iversion.h +++ b/include/linux/iversion.h @@ -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 -- 2.21.0