Merge git://git.infradead.org/mtd-2.6

* git://git.infradead.org/mtd-2.6: (199 commits)
  [MTD] NAND: Fix breakage all over the place
  [PATCH] NAND: fix remaining OOB length calculation
  [MTD] NAND Fixup NDFC merge brokeness
  [MTD NAND] S3C2410 driver cleanup
  [MTD NAND] s3c24x0 board: Fix clock handling, ensure proper initialisation.
  [JFFS2] Check CRC32 on dirent and data nodes each time they're read
  [JFFS2] When retiring nextblock, allocate a node_ref for the wasted space
  [JFFS2] Mark XATTR support as experimental, for now
  [JFFS2] Don't trust node headers before the CRC is checked.
  [MTD] Restore MTD_ROM and MTD_RAM types
  [MTD] assume mtd->writesize is 1 for NOR flashes
  [MTD NAND] Fix s3c2410 NAND driver so it at least _looks_ like it compiles
  [MTD] Prepare physmap for 64-bit-resources
  [JFFS2] Fix more breakage caused by janitorial meddling.
  [JFFS2] Remove stray __exit from jffs2_compressors_exit()
  [MTD] Allow alternate JFFS2 mount variant for root filesystem.
  [MTD] Disconnect struct mtd_info from ABI
  [MTD] replace MTD_RAM with MTD_GENERIC_TYPE
  [MTD] replace MTD_ROM with MTD_GENERIC_TYPE
  [MTD] remove a forgotten MTD_XIP
  ...

1 files changed, 21 insertions, 0 deletions

diff --git a/fs/jffs2/README.Locking b/fs/jffs2/README.Locking
index b7943439b6ec..c8f0bd64e53e 100644
--- a/fs/jffs2/README.Locking
+++ b/fs/jffs2/README.Locking
@@ -150,3 +150,24 @@ the buffer.
 
 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.