[Patch] Fix up return value from mq_open()

[Doug Ledford <dledford@xsintricity.com>]

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Commit d40dcdb ipc/mqueue.c: fix mq_open() return value
changed the return value for mq_open() to return

EMFILE - The process already has the maximum number of files and
               message queues open.

instead of

ENOMEM - Insufficient memory.

While the portion of d40dcdb that introduced using ERR_PTR() to
propagate the condition were helpful, the change to the type of error
was not.  The specific test that was failing was a memory space test.
It can fail if there are too many message queues open and this one would
cause us to exceed the tasks counter for memory bytes capacity (aka, int
wrap) or it can fail if the total number of bytes already allocated plus
this allocation will exceed the user's RLIMIT for POSIX message queues.
 However, depending on the values passed in via an attribute struct,
this could happen on the 1st file or the 100th file.  There is no direct
relationship to file count in this test.  There is only a direct
correlation to memory usage.  Therefore return the code to giving ENOMEM
instead of EMFILE.

(If the attachment is a problem I'll find another mailer to use and resend).

-- 
Doug Ledford <dledford@xsintricity.com>
              GPG KeyID: D30533DF




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commit b80e4058e2b4234fb33a9fd84b4ce288e8ba65cb
Author: Doug Ledford <dledford@redhat.com>
Date:   Thu Sep 29 19:02:47 2011 -0400

    ipc/mqueue: make the error returns match the conditions
    
    We should not return -EMFILE when the problem is memory usage.
    
    Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 0474ddb..3e53604 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -165,7 +165,7 @@ static struct inode *mqueue_get_inode(struct super_block *sb,
 		    u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) {
 			spin_unlock(&mq_lock);
 			/* mqueue_evict_inode() releases info->messages */
-			ret = -EMFILE;
+			ret = -ENOMEM;
 			goto out_inode;
 		}
 		u->mq_bytes += mq_bytes;

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