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Date: Tue, 23 Jun 2020 21:56:54 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, "zhangyi (F)" <yi.zhang@...wei.com>,
Jan Kara <jack@...e.cz>, Theodore Tso <tytso@....edu>
Subject: [PATCH 5.7 417/477] ext4, jbd2: ensure panic by fix a race between jbd2 abort and ext4 error handlers
From: zhangyi (F) <yi.zhang@...wei.com>
commit 7b97d868b7ab2448859668de9222b8af43f76e78 upstream.
In the ext4 filesystem with errors=panic, if one process is recording
errno in the superblock when invoking jbd2_journal_abort() due to some
error cases, it could be raced by another __ext4_abort() which is
setting the SB_RDONLY flag but missing panic because errno has not been
recorded.
jbd2_journal_commit_transaction()
jbd2_journal_abort()
journal->j_flags |= JBD2_ABORT;
jbd2_journal_update_sb_errno()
| ext4_journal_check_start()
| __ext4_abort()
| sb->s_flags |= SB_RDONLY;
| if (!JBD2_REC_ERR)
| return;
journal->j_flags |= JBD2_REC_ERR;
Finally, it will no longer trigger panic because the filesystem has
already been set read-only. Fix this by introduce j_abort_mutex to make
sure journal abort is completed before panic, and remove JBD2_REC_ERR
flag.
Fixes: 4327ba52afd03 ("ext4, jbd2: ensure entering into panic after recording an error in superblock")
Signed-off-by: zhangyi (F) <yi.zhang@...wei.com>
Reviewed-by: Jan Kara <jack@...e.cz>
Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/r/20200609073540.3810702-1-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
fs/ext4/super.c | 16 +++++-----------
fs/jbd2/journal.c | 17 ++++++++++++-----
include/linux/jbd2.h | 6 +++++-
3 files changed, 22 insertions(+), 17 deletions(-)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -522,9 +522,6 @@ static void ext4_handle_error(struct sup
smp_wmb();
sb->s_flags |= SB_RDONLY;
} else if (test_opt(sb, ERRORS_PANIC)) {
- if (EXT4_SB(sb)->s_journal &&
- !(EXT4_SB(sb)->s_journal->j_flags & JBD2_REC_ERR))
- return;
panic("EXT4-fs (device %s): panic forced after error\n",
sb->s_id);
}
@@ -725,23 +722,20 @@ void __ext4_abort(struct super_block *sb
va_end(args);
if (sb_rdonly(sb) == 0) {
- ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only");
EXT4_SB(sb)->s_mount_flags |= EXT4_MF_FS_ABORTED;
+ if (EXT4_SB(sb)->s_journal)
+ jbd2_journal_abort(EXT4_SB(sb)->s_journal, -EIO);
+
+ ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only");
/*
* Make sure updated value of ->s_mount_flags will be visible
* before ->s_flags update
*/
smp_wmb();
sb->s_flags |= SB_RDONLY;
- if (EXT4_SB(sb)->s_journal)
- jbd2_journal_abort(EXT4_SB(sb)->s_journal, -EIO);
}
- if (test_opt(sb, ERRORS_PANIC) && !system_going_down()) {
- if (EXT4_SB(sb)->s_journal &&
- !(EXT4_SB(sb)->s_journal->j_flags & JBD2_REC_ERR))
- return;
+ if (test_opt(sb, ERRORS_PANIC) && !system_going_down())
panic("EXT4-fs panic from previous error\n");
- }
}
void __ext4_msg(struct super_block *sb,
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1140,6 +1140,7 @@ static journal_t *journal_init_common(st
init_waitqueue_head(&journal->j_wait_commit);
init_waitqueue_head(&journal->j_wait_updates);
init_waitqueue_head(&journal->j_wait_reserved);
+ mutex_init(&journal->j_abort_mutex);
mutex_init(&journal->j_barrier);
mutex_init(&journal->j_checkpoint_mutex);
spin_lock_init(&journal->j_revoke_lock);
@@ -1402,7 +1403,8 @@ static int jbd2_write_superblock(journal
printk(KERN_ERR "JBD2: Error %d detected when updating "
"journal superblock for %s.\n", ret,
journal->j_devname);
- jbd2_journal_abort(journal, ret);
+ if (!is_journal_aborted(journal))
+ jbd2_journal_abort(journal, ret);
}
return ret;
@@ -2154,6 +2156,13 @@ void jbd2_journal_abort(journal_t *journ
transaction_t *transaction;
/*
+ * Lock the aborting procedure until everything is done, this avoid
+ * races between filesystem's error handling flow (e.g. ext4_abort()),
+ * ensure panic after the error info is written into journal's
+ * superblock.
+ */
+ mutex_lock(&journal->j_abort_mutex);
+ /*
* ESHUTDOWN always takes precedence because a file system check
* caused by any other journal abort error is not required after
* a shutdown triggered.
@@ -2167,6 +2176,7 @@ void jbd2_journal_abort(journal_t *journ
journal->j_errno = errno;
jbd2_journal_update_sb_errno(journal);
}
+ mutex_unlock(&journal->j_abort_mutex);
return;
}
@@ -2188,10 +2198,7 @@ void jbd2_journal_abort(journal_t *journ
* layer could realise that a filesystem check is needed.
*/
jbd2_journal_update_sb_errno(journal);
-
- write_lock(&journal->j_state_lock);
- journal->j_flags |= JBD2_REC_ERR;
- write_unlock(&journal->j_state_lock);
+ mutex_unlock(&journal->j_abort_mutex);
}
/**
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -766,6 +766,11 @@ struct journal_s
int j_errno;
/**
+ * @j_abort_mutex: Lock the whole aborting procedure.
+ */
+ struct mutex j_abort_mutex;
+
+ /**
* @j_sb_buffer: The first part of the superblock buffer.
*/
struct buffer_head *j_sb_buffer;
@@ -1247,7 +1252,6 @@ JBD2_FEATURE_INCOMPAT_FUNCS(csum3, CSUM
#define JBD2_ABORT_ON_SYNCDATA_ERR 0x040 /* Abort the journal on file
* data write error in ordered
* mode */
-#define JBD2_REC_ERR 0x080 /* The errno in the sb has been recorded */
/*
* Function declarations for the journaling transaction and buffer
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