Ordering constraints:
Lock wbuf_sem last, after the alloc_sem or and f->sem.
-
-
- c->xattr_sem
- ------------
-
-This read/write semaphore protects against concurrent access to the
-xattr related objects which include stuff in superblock and ic->xref.
-In read-only path, write-semaphore is too much exclusion. It's enough
-by read-semaphore. But you must hold write-semaphore when updating,
-creating or deleting any xattr related object.
-
-Once xattr_sem released, there would be no assurance for the existence
-of those objects. Thus, a series of processes is often required to retry,
-when updating such a object is necessary under holding read semaphore.
-For example, do_jffs2_getxattr() holds read-semaphore to scan xref and
-xdatum at first. But it retries this process with holding write-semaphore
-after release read-semaphore, if it's necessary to load name/value pair
-from medium.
-
-Ordering constraints:
- Lock xattr_sem last, after the alloc_sem.
git://git.onelab.eu / linux-2.6.git / blobdiff