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Re: [PATCH 1/3] xfs: kill XBF_LOCK

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 1/3] xfs: kill XBF_LOCK
From: Mark Tinguely <tinguely@xxxxxxx>
Date: Tue, 10 Apr 2012 10:00:18 -0500
Cc: xfs@xxxxxxxxxxx
In-reply-to: <1334052213-26870-2-git-send-email-david@xxxxxxxxxxxxx>
References: <1334052213-26870-1-git-send-email-david@xxxxxxxxxxxxx> <1334052213-26870-2-git-send-email-david@xxxxxxxxxxxxx>
User-agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:9.0) Gecko/20120122 Thunderbird/9.0
On 04/10/12 05:03, Dave Chinner wrote:
From: Dave Chinner<dchinner@xxxxxxxxxx>

Buffers are always returned locked from the lookup routines. Hence
we don't need to tell the lookup routines to return locked buffers,
on to try and lock them. Remove XBF_LOCK from all the callers and
from internal buffer cache usage.

Signed-off-by: Dave Chinner<dchinner@xxxxxxxxxx>
---
  fs/xfs/xfs_attr.c        |    5 ++---
  fs/xfs/xfs_attr_leaf.c   |    2 +-
  fs/xfs/xfs_buf.c         |   20 +++++---------------
  fs/xfs/xfs_buf.h         |    4 +---
  fs/xfs/xfs_fsops.c       |   13 +++++--------
  fs/xfs/xfs_ialloc.c      |    3 +--
  fs/xfs/xfs_inode.c       |   16 +++++++---------
  fs/xfs/xfs_log_recover.c |    7 +++----
  fs/xfs/xfs_rw.c          |    2 +-
  fs/xfs/xfs_trans_buf.c   |    4 ++--
  fs/xfs/xfs_vnodeops.c    |    2 +-
  11 files changed, 29 insertions(+), 49 deletions(-)


diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 7a945fd..8d76df1 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -179,7 +179,7 @@ xfs_buf_alloc(
        /*
         * We don't want certain flags to appear in b_flags.
         */
-       flags&= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
+       flags&= ~(XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);

        atomic_set(&bp->b_hold, 1);
        atomic_set(&bp->b_lru_ref, 1);
@@ -578,19 +578,14 @@ found:
                if (unlikely(error)) {
                        xfs_warn(target->bt_mount,
                                "%s: failed to map pages\n", __func__);
-                       goto no_buffer;
+                       xfs_buf_relse(bp);
+                       return NULL;
                }
        }

        XFS_STATS_INC(xb_get);
        trace_xfs_buf_get(bp, flags, _RET_IP_);
        return bp;
-
-no_buffer:
-       if (flags&  (XBF_LOCK | XBF_TRYLOCK))
-               xfs_buf_unlock(bp);
-       xfs_buf_rele(bp);
-       return NULL;
  }


Do you have a new copy of the "xfs: fix buffer lookup race on allocation failure" patch. It would go about here in the sources.

The reason I ask, the sources that I have for xfs_buf_get() seems to still have a "goto no_buffer" for the failed xfs_buf_allocate_memory() call and this patch removes that call. I did not find anything in the 8 buf clean-up series that would alter this area.


Thank-you,

--Mark Tinguely <tinguely@xxxxxxx>

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