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NFS: Fix another nfs_wb_page() deadlock

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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>
This commit is contained in:
Trond Myklebust 2010-05-26 08:42:24 -04:00
parent c5efa5fc91
commit 0522f6aded
1 changed files with 5 additions and 2 deletions
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7
fs/nfs/write.c
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@ -1518,14 +1518,17 @@ int nfs_wb_page(struct inode *inode, struct page *page)
};
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;
}