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authorChristoph Hellwig <hch@lst.de>2008-09-09 14:02:01 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-09-09 14:51:15 -0400
commitadaae7215e5130e5ce1ac3ee390e5a23101b09b2 (patch)
treec809c8ac79e74f9f698a5d33dd0b6f8956869294 /Documentation
parent82a28c794f27aac17d7a3ebd7f14d731a11a5532 (diff)
update Documentation/filesystems/Locking for 2.6.27 changes
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 <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/filesystems/Locking15
1 files changed, 4 insertions, 11 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 680fb566b928..8362860e21a7 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -144,8 +144,8 @@ prototypes:
144 void (*kill_sb) (struct super_block *); 144 void (*kill_sb) (struct super_block *);
145locking rules: 145locking rules:
146 may block BKL 146 may block BKL
147get_sb yes yes 147get_sb yes no
148kill_sb yes yes 148kill_sb yes no
149 149
150->get_sb() returns error or 0 with locked superblock attached to the vfsmount 150->get_sb() returns error or 0 with locked superblock attached to the vfsmount
151(exclusive on ->s_umount). 151(exclusive on ->s_umount).
@@ -409,12 +409,12 @@ ioctl: yes (see below)
409unlocked_ioctl: no (see below) 409unlocked_ioctl: no (see below)
410compat_ioctl: no 410compat_ioctl: no
411mmap: no 411mmap: no
412open: maybe (see below) 412open: no
413flush: no 413flush: no
414release: no 414release: no
415fsync: no (see below) 415fsync: no (see below)
416aio_fsync: no 416aio_fsync: no
417fasync: yes (see below) 417fasync: no
418lock: yes 418lock: yes
419readv: no 419readv: no
420writev: no 420writev: no
@@ -431,13 +431,6 @@ For many filesystems, it is probably safe to acquire the inode
431semaphore. Note some filesystems (i.e. remote ones) provide no 431semaphore. Note some filesystems (i.e. remote ones) provide no
432protection for i_size so you will need to use the BKL. 432protection for i_size so you will need to use the BKL.
433 433
434->open() locking is in-transit: big lock partially moved into the methods.
435The only exception is ->open() in the instances of file_operations that never
436end up in ->i_fop/->proc_fops, i.e. ones that belong to character devices
437(chrdev_open() takes lock before replacing ->f_op and calling the secondary
438method. As soon as we fix the handling of module reference counters all
439instances of ->open() will be called without the BKL.
440
441Note: ext2_release() was *the* source of contention on fs-intensive 434Note: ext2_release() was *the* source of contention on fs-intensive
442loads and dropping BKL on ->release() helps to get rid of that (we still 435loads and dropping BKL on ->release() helps to get rid of that (we still
443grab BKL for cases when we close a file that had been opened r/w, but that 436grab BKL for cases when we close a file that had been opened r/w, but that