From 66488cebc779518874605f6335e40af66a1fb1ba Mon Sep 17 00:00:00 2001
From: bwzhou <bwzhou>
Date: Mon, 17 Dec 2007 07:30:56 +0000
Subject: [PATCH] Branch HEAD b=14138 r=adilger, nikita
resolve deadlock on i_size_read() introduced by race condition of i_size_write();
Use old size assignment to avoid deadlock (bz14326).
---
lustre/llite/dir.c | 5 ++++-
lustre/llite/llite_lib.c | 8 ++++++--
lustre/llite/llite_mmap.c | 10 ++++++++--
3 files changed, 18 insertions(+), 5 deletions(-)
diff --git a/lustre/llite/dir.c b/lustre/llite/dir.c
index 290ae72e3e..ebea76c099 100644
--- a/lustre/llite/dir.c
+++ b/lustre/llite/dir.c
@@ -162,8 +162,11 @@ static int ll_dir_readpage(struct file *file, struct page *page)
/* Swabbed by mdc_readpage() */
LASSERT(lustre_rep_swabbed(request, REPLY_REC_OFF));
- if (body->valid & OBD_MD_FLSIZE)
+ if (body->valid & OBD_MD_FLSIZE) {
+ ll_inode_size_lock(inode, 0);
i_size_write(inode, body->size);
+ ll_inode_size_unlock(inode, 0);
+ }
SetPageUptodate(page);
}
ptlrpc_req_finished(request);
diff --git a/lustre/llite/llite_lib.c b/lustre/llite/llite_lib.c
index 77f615f5e1..2f6fbabe1e 100644
--- a/lustre/llite/llite_lib.c
+++ b/lustre/llite/llite_lib.c
@@ -1696,13 +1696,17 @@ void ll_update_inode(struct inode *inode, struct lustre_md *md)
"the size got from MDS\n",
inode->i_ino, lli->lli_flags);
} else {
- i_size_write(inode, body->size);
+ /* Use old size assignment to avoid
+ * deadlock bz14138 & bz14326 */
+ inode->i_size = body->size;
lli->lli_flags |= LLIF_MDS_SIZE_LOCK;
}
ldlm_lock_decref(&lockh, mode);
}
} else {
- i_size_write(inode, body->size);
+ /* Use old size assignment to avoid
+ * deadlock bz14138 & bz14326 */
+ inode->i_size = body->size;
}
if (body->valid & OBD_MD_FLBLOCKS)
diff --git a/lustre/llite/llite_mmap.c b/lustre/llite/llite_mmap.c
index 025ad7b8cc..7d2651b223 100644
--- a/lustre/llite/llite_mmap.c
+++ b/lustre/llite/llite_mmap.c
@@ -400,14 +400,20 @@ struct page *ll_nopage(struct vm_area_struct *vma, unsigned long address,
/* XXX change inode size without ll_inode_size_lock() held!
* there is a race condition with truncate path. (see
* ll_extent_lock) */
- /* region is within kms and, hence, within real file size (A).
+ /* XXX i_size_write() is not used because it is not safe to
+ * take the ll_inode_size_lock() due to a potential lock
+ * inversion (bug 6077). And since it's not safe to use
+ * i_size_write() without a covering mutex we do the
+ * assignment directly. It is not critical that the
+ * size be correct. */
+ /* region is within kms and, hence, within real file size (A).
* We need to increase i_size to cover the read region so that
* generic_file_read() will do its job, but that doesn't mean
* the kms size is _correct_, it is only the _minimum_ size.
* If someone does a stat they will get the correct size which
* will always be >= the kms value here. b=11081 */
if (i_size_read(inode) < kms) {
- i_size_write(inode, kms);
+ inode->i_size = kms;
CDEBUG(D_INODE, "ino=%lu, updating i_size %llu\n",
inode->i_ino, i_size_read(inode));
}
--
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