Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a13cbe375303585fec1425135ed54adb62be41fc
Commit:     a13cbe375303585fec1425135ed54adb62be41fc
Parent:     a7d2b2bdc9a0b55d5b08e15756c7e65c48c4bca5
Author:     Josef Whiter <[EMAIL PROTECTED]>
AuthorDate: Fri Feb 23 12:49:51 2007 -0500
Committer:  Steven Whitehouse <[EMAIL PROTECTED]>
CommitDate: Wed Mar 7 13:58:02 2007 -0500

    [GFS2] fix hangup when multiple processes are trying to write to the same 
file
    
    This fixes a problem I encountered while running bonnie++.  When you have 
one
    thread that opens a file and starts to write to it, and then another thread 
that
    tries to open and write to the same file, the second thread will loop 
forever
    trying to grab the inode lock for that inode.  Basically we come in through
    generic_buffered_file_write, which calls gfs2_prepare_write, which then 
attempts
    to grab the glock.  Because we don't own the lock, gfs2_prepare_write gets
    GLR_TRYFAILED, which returns AOP_TRUNCATED_PAGE to 
generic_buffered_file_write.
    At this point generic_buffered_file_write loops around again and immediately
    retries the prepare_write.  This means that the second process never gets 
off of
    the processor in order to allow the process that holds the lock to finish 
its
    work and let go of the lock.  This patch makes gfs2_glock_nq schedule() if 
it
    gets back a GLR_TRYFAILED, which resolves this problem.
    
    Signed-off-by: Josef Whiter <[EMAIL PROTECTED]>
    Signed-off-by: Steven Whitehouse <[EMAIL PROTECTED]>
---
 fs/gfs2/ops_address.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index 56e3359..b3b7e84 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -266,9 +266,11 @@ skip_lock:
 out:
        return error;
 out_unlock:
-       if (error == GLR_TRYFAILED)
-               error = AOP_TRUNCATED_PAGE;
        unlock_page(page);
+       if (error == GLR_TRYFAILED) {
+               error = AOP_TRUNCATED_PAGE;
+               yield();
+       }
        if (do_unlock)
                gfs2_holder_uninit(&gh);
        goto out;
@@ -364,6 +366,7 @@ static int gfs2_prepare_write(struct file *file, struct 
page *page,
                if (error == GLR_TRYFAILED) {
                        unlock_page(page);
                        error = AOP_TRUNCATED_PAGE;
+                       yield();
                }
                goto out_uninit;
        }
-
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