staging: lustre: fid: convert lcs_mutex to a spinlock

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There is only one place where this lock is held
while the task might sleep - in
  ldebugfs_fid_space_seq_write()
while ldebugfs_fid_write_common() is called.

This call can easily be taken out of the locked region
by asking it to parse the user data into a local variable,
and then copying that variable into ->lcs_space while
holding the lock.

Note that ldebugfs_gid_write_common returns >0 on
success, so use that to gate updating ->lcs_space.

So make that change, and convert lcs_mutex to a spinlock
named lcs_lock.  spinlocks are slightly cheaper than mutexes
and using one makes is clear that the lock is only held for
a short time.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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This commit is contained in:

NeilBrown 2018-02-20 13:23:38 +11:00 • committed by Greg Kroah-Hartman

parent ef8e5dbbb0

commit daa5611c71

3 changed files with 29 additions and 26 deletions

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24

drivers/staging/lustre/lustre/fid/fid_request.c

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29

drivers/staging/lustre/lustre/fid/lproc_fid.c

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2

drivers/staging/lustre/lustre/include/lustre_fid.h

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