In the 2.6.27 circle ->fasync lost the BKL, and the last remaining
->open variant that takes the BKL is also gone. ->get_sb and ->kill_sb
didn't have BKL forever, so updated the entries while we're at that.
Signed-off-by: Christoph Hellwig <email@example.com>
--- linux-2.6.orig/Documentation/filesystems/Locking 2008-09-09 19:57:03.000000000 +0200
+++ linux-2.6/Documentation/filesystems/Locking 2008-09-09 19:59:46.000000000 +0200
@@ -144,8 +144,8 @@ prototypes:
void (*kill_sb) (struct super_block *);
may block BKL
-get_sb yes yes
-kill_sb yes yes
+get_sb yes no
+kill_sb yes no
->get_sb() returns error or 0 with locked superblock attached to the vfsmount
(exclusive on ->s_umount).
@@ -409,12 +409,12 @@ ioctl: yes (see below)
unlocked_ioctl: no (see below)
-open: maybe (see below)
fsync: no (see below)
-fasync: yes (see below)
@@ -431,13 +431,6 @@ For many filesystems, it is probably saf
semaphore. Note some filesystems (i.e. remote ones) provide no
protection for i_size so you will need to use the BKL.
-->open() locking is in-transit: big lock partially moved into the methods.
-The only exception is ->open() in the instances of file_operations that never
-end up in ->i_fop/->proc_fops, i.e. ones that belong to character devices
-(chrdev_open() takes lock before replacing ->f_op and calling the secondary
-method. As soon as we fix the handling of module reference counters all
-instances of ->open() will be called without the BKL.
Note: ext2_release() was *the* source of contention on fs-intensive
loads and dropping BKL on ->release() helps to get rid of that (we still
grab BKL for cases when we close a file that had been opened r/w, but that