ext4: Convert to new freezing mechanism
We remove most of frozen checks since upper layer takes care of blocking all
writes. We have to handle protection in ext4_page_mkwrite() in a special way
because we cannot use generic block_page_mkwrite(). Also we add a freeze
protection to ext4_evict_inode() so that iput() of unlinked inode cannot modify
a frozen filesystem (we cannot easily instrument ext4_journal_start() /
ext4_journal_stop() with freeze protection because we are missing the
superblock pointer in ext4_journal_stop() in nojournal mode).
CC: linux-ext4@vger.kernel.org
CC: "Theodore Ts'o" <tytso@mit.edu>
BugLink: https://bugs.launchpad.net/bugs/897421
Tested-by: Kamal Mostafa <kamal@canonical.com>
Tested-by: Peter M. Petrakis <peter.petrakis@canonical.com>
Tested-by: Dann Frazier <dann.frazier@canonical.com>
Tested-by: Massimo Morana <massimo.morana@canonical.com>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 02bc8cb..301e1c2 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -233,6 +233,11 @@
if (is_bad_inode(inode))
goto no_delete;
+ /*
+ * Protect us against freezing - iput() caller didn't have to have any
+ * protection against it
+ */
+ sb_start_intwrite(inode->i_sb);
handle = ext4_journal_start(inode, ext4_blocks_for_truncate(inode)+3);
if (IS_ERR(handle)) {
ext4_std_error(inode->i_sb, PTR_ERR(handle));
@@ -242,6 +247,7 @@
* cleaned up.
*/
ext4_orphan_del(NULL, inode);
+ sb_end_intwrite(inode->i_sb);
goto no_delete;
}
@@ -273,6 +279,7 @@
stop_handle:
ext4_journal_stop(handle);
ext4_orphan_del(NULL, inode);
+ sb_end_intwrite(inode->i_sb);
goto no_delete;
}
}
@@ -301,6 +308,7 @@
else
ext4_free_inode(handle, inode);
ext4_journal_stop(handle);
+ sb_end_intwrite(inode->i_sb);
return;
no_delete:
ext4_clear_inode(inode); /* We must guarantee clearing of inode... */
@@ -4701,11 +4709,7 @@
get_block_t *get_block;
int retries = 0;
- /*
- * This check is racy but catches the common case. We rely on
- * __block_page_mkwrite() to do a reliable check.
- */
- vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+ sb_start_pagefault(inode->i_sb);
/* Delalloc case is easy... */
if (test_opt(inode->i_sb, DELALLOC) &&
!ext4_should_journal_data(inode) &&
@@ -4773,5 +4777,6 @@
out_ret:
ret = block_page_mkwrite_return(ret);
out:
+ sb_end_pagefault(inode->i_sb);
return ret;
}