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authorJan Kara <jack@suse.cz>2009-02-22 21:09:59 -0500
committerTheodore Ts'o <tytso@mit.edu>2009-02-22 21:09:59 -0500
commitebd3610b110bbb18ea6f9f2aeed1e1068c537227 (patch)
treea7ecd4c6ef1d05619abeefea831e8f73ffadda11
parent05bf9e839d9de4e8a094274a0a2fd07beb47eaf1 (diff)
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>
-rw-r--r--fs/ext4/inode.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index cbd2ca99d113..51cdd13e1c31 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -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);
@@ -1377,7 +1381,7 @@ retry:
*pagep = page;
ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
- ext4_get_block);
+ ext4_get_block);
if (!ret && ext4_should_journal_data(inode)) {
ret = walk_page_buffers(handle, page_buffers(page),
@@ -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) {