Re: Re: [PATCH TRIVIVAL] ceph: Move the place for EOLDSNAPC handle in ceph_aio_write to easily understand

[majianpeng <majianpeng@gmail.com>]

>Looks good; I've applied this to the tree.  Canyou review the below patch 
>while we are looking at this code?
>
>Thanks!
>sage
>
>From 26d0d7b213d87db0ef46e885ae749c27395c11b1 Mon Sep 17 00:00:00 2001
>From: Sage Weil <sage@inktank.com>
>Date: Thu, 8 Aug 2013 09:39:44 -0700
>Subject: [PATCH] ceph: replace hold_mutex flag with goto
>
>All of the early exit paths need to drop the mutex; it is only the normal
>path through the function that does not.  Skip the unlock in that case
>with a goto out_unlocked.
>
>Signed-off-by: Sage Weil <sage@inktank.com>
>---
> fs/ceph/file.c | 11 ++++-------
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
>diff --git a/fs/ceph/file.c b/fs/ceph/file.c
>index 7478d5d..a17ffe4 100644
>--- a/fs/ceph/file.c
>+++ b/fs/ceph/file.c
>@@ -710,13 +710,11 @@ static ssize_t ceph_aio_write(struct kiocb *iocb, const struct iovec *iov,
> 		&ceph_sb_to_client(inode->i_sb)->client->osdc;
> 	ssize_t count, written = 0;
> 	int err, want, got;
>-	bool hold_mutex;
> 
> 	if (ceph_snap(inode) != CEPH_NOSNAP)
> 		return -EROFS;
> 
> 	mutex_lock(&inode->i_mutex);
>-	hold_mutex = true;
> 
> 	err = generic_segment_checks(iov, &nr_segs, &count, VERIFY_READ);
> 	if (err)
>@@ -772,7 +770,6 @@ retry_snap:
> 				inode, ceph_vinop(inode),
> 				pos, (unsigned)iov->iov_len);
> 			mutex_lock(&inode->i_mutex);
>-			hold_mutex = true;
> 			goto retry_snap;
> 		}
> 	} else {
>@@ -781,7 +778,6 @@ retry_snap:
> 						      count, 0);
> 		mutex_unlock(&inode->i_mutex);
> 	}
>-	hold_mutex = false;
> 
> 	if (written >= 0) {
> 		int dirty;
>@@ -805,11 +801,12 @@ retry_snap:
> 			written = err;
> 	}
> 
>+	goto out_unlocked;
>+
> out:
>-	if (hold_mutex)
>-		mutex_unlock(&inode->i_mutex);
>+	mutex_unlock(&inode->i_mutex);
>+out_unlocked:
> 	current->backing_dev_info = NULL;
>-
> 	return written ? written : err;
> }
> 
>-- 
>1.8.1.2
>
Hi sage,
	It's ok.
	BTW, i had a question about EOLDSNAPC.Now for a sync-write,if it met EOLDSNAPC, it will retry.
The rewrite is for all bio.Supported a sync-write crossed multi stripe.
Q1:Is there a chance that for some stripe-write it din't met EOLDSNAPC,the later met?
Q2:If Q1 occured, can we only rewrite the stripe which met EOLDSNAPCE?

Thanks!
Jianpeng Ma