Commit ebd3610b authored Feb 22, 2009 by Jan Kara Committed by Theodore Ts'o Feb 22, 2009

ext4: Fix deadlock in ext4_write_begin() and ext4_da_write_begin()

Functions ext4_write_begin() and ext4_da_write_begin() call
grab_cache_page_write_begin() without AOP_FLAG_NOFS. Thus it
can happen that page reclaim is triggered in that function
and it recurses back into the filesystem (or some other filesystem).
But this can lead to various problems as a transaction is already
started at that point. Add the necessary flag.

http://bugzilla.kernel.org/show_bug.cgi?id=11688



Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

parent 05bf9e83

fs/ext4/inode.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -1368,6 +1368,10 @@ retry:
		goto out;
		}

		/* We cannot recurse into the filesystem as the transaction is already
		* started */
		flags \|= AOP_FLAG_NOFS;

		page = grab_cache_page_write_begin(mapping, index, flags);
		if (!page) {
		ext4_journal_stop(handle);
		@@ -2667,6 +2671,9 @@ retry:
		ret = PTR_ERR(handle);
		goto out;
		}
		/* We cannot recurse into the filesystem as the transaction is already
		* started */
		flags \|= AOP_FLAG_NOFS;

		page = grab_cache_page_write_begin(mapping, index, flags);
		if (!page) {

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