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authorJan Kara <jack@suse.cz>2010-07-14 07:56:33 +0200
committerJoel Becker <joel.becker@oracle.com>2010-07-15 15:17:47 -0700
commit13ceef099edd2b70c5a6f3a9ef5d6d97cda2e096 (patch)
tree5d65c397e9e85abe11a6fb0ebf3a69e8a4e91e0d /include
parenta39953dd95ff10e311083d94f4f95c348cb22464 (diff)
downloadlinux-2.6.34-ux500-13ceef099edd2b70c5a6f3a9ef5d6d97cda2e096.tar.gz
jbd2/ocfs2: Fix block checksumming when a buffer is used in several transactions
OCFS2 uses t_commit trigger to compute and store checksum of the just committed blocks. When a buffer has b_frozen_data, checksum is computed for it instead of b_data but this can result in an old checksum being written to the filesystem in the following scenario: 1) transaction1 is opened 2) handle1 is opened 3) journal_access(handle1, bh) - This sets jh->b_transaction to transaction1 4) modify(bh) 5) journal_dirty(handle1, bh) 6) handle1 is closed 7) start committing transaction1, opening transaction2 8) handle2 is opened 9) journal_access(handle2, bh) - This copies off b_frozen_data to make it safe for transaction1 to commit. jh->b_next_transaction is set to transaction2. 10) jbd2_journal_write_metadata() checksums b_frozen_data 11) the journal correctly writes b_frozen_data to the disk journal 12) handle2 is closed - There was no dirty call for the bh on handle2, so it is never queued for any more journal operation 13) Checkpointing finally happens, and it just spools the bh via normal buffer writeback. This will write b_data, which was never triggered on and thus contains a wrong (old) checksum. This patch fixes the problem by calling the trigger at the moment data is frozen for journal commit - i.e., either when b_frozen_data is created by do_get_write_access or just before we write a buffer to the log if b_frozen_data does not exist. We also rename the trigger to t_frozen as that better describes when it is called. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/jbd2.h11
1 files changed, 6 insertions, 5 deletions
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index a4d2e9f7088..adf832dec3f 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1026,11 +1026,12 @@ void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);
struct jbd2_buffer_trigger_type {
/*
- * Fired just before a buffer is written to the journal.
- * mapped_data is a mapped buffer that is the frozen data for
- * commit.
+ * Fired a the moment data to write to the journal are known to be
+ * stable - so either at the moment b_frozen_data is created or just
+ * before a buffer is written to the journal. mapped_data is a mapped
+ * buffer that is the frozen data for commit.
*/
- void (*t_commit)(struct jbd2_buffer_trigger_type *type,
+ void (*t_frozen)(struct jbd2_buffer_trigger_type *type,
struct buffer_head *bh, void *mapped_data,
size_t size);
@@ -1042,7 +1043,7 @@ struct jbd2_buffer_trigger_type {
struct buffer_head *bh);
};
-extern void jbd2_buffer_commit_trigger(struct journal_head *jh,
+extern void jbd2_buffer_frozen_trigger(struct journal_head *jh,
void *mapped_data,
struct jbd2_buffer_trigger_type *triggers);
extern void jbd2_buffer_abort_trigger(struct journal_head *jh,