| Date | Thu, 01 Jul 2010 10:44:26 -0700 | From | Greg KH <> | Subject | [176/200] NFS: Fix another nfs_wb_page() deadlock |
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2.6.34-stable review patch. If anyone has any objections, please let me know.
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From: Trond Myklebust <Trond.Myklebust@netapp.com>
commit 0522f6adedd2736cbca3c0e16ca51df668993eee upstream.
J.R. Okajima reports that the call to sync_inode() in nfs_wb_page() can deadlock with other writeback flush calls. It boils down to the fact that we cannot ever call writeback_single_inode() while holding a page lock (even if we do set nr_to_write to zero) since another process may already be waiting in the call to do_writepages(), and so will deny us the I_SYNC lock.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/nfs/write.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -1518,14 +1518,17 @@ int nfs_wb_page(struct inode *inode, str }; int ret; - while(PagePrivate(page)) { + for (;;) { wait_on_page_writeback(page); if (clear_page_dirty_for_io(page)) { ret = nfs_writepage_locked(page, &wbc); if (ret < 0) goto out_error; + continue; } - ret = sync_inode(inode, &wbc); + if (!PagePrivate(page)) + break; + ret = nfs_commit_inode(inode, FLUSH_SYNC); if (ret < 0) goto out_error; }
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