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r: 109708
b: refs/heads/master
c: adaae72
h: refs/heads/master
v: v3
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Christoph Hellwig authored and Linus Torvalds committed Sep 9, 2008
1 parent 029e9a9 commit cb344fa
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2 changes: 1 addition & 1 deletion [refs]
Original file line number Diff line number Diff line change
@@ -1,2 +1,2 @@
---
refs/heads/master: 82a28c794f27aac17d7a3ebd7f14d731a11a5532
refs/heads/master: adaae7215e5130e5ce1ac3ee390e5a23101b09b2
15 changes: 4 additions & 11 deletions trunk/Documentation/filesystems/Locking
Original file line number Diff line number Diff line change
Expand Up @@ -144,8 +144,8 @@ prototypes:
void (*kill_sb) (struct super_block *);
locking rules:
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).
Expand Down Expand Up @@ -409,12 +409,12 @@ ioctl: yes (see below)
unlocked_ioctl: no (see below)
compat_ioctl: no
mmap: no
open: maybe (see below)
open: no
flush: no
release: no
fsync: no (see below)
aio_fsync: no
fasync: yes (see below)
fasync: no
lock: yes
readv: no
writev: no
Expand All @@ -431,13 +431,6 @@ For many filesystems, it is probably safe to acquire the inode
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
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