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authorBrian Foster <bfoster@redhat.com>2017-09-17 14:06:51 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-09-20 08:20:00 +0200
commit35093926c2f8bd259e50b73685f638095cc59c89 (patch)
tree46054beffbdcad943922dbcbff6c918bb3a32b1a
parent0800356def7f3ede34986adeeb03235176297eb0 (diff)
downloadlinux-linaro-stable-35093926c2f8bd259e50b73685f638095cc59c89.tar.gz
xfs: fix recovery failure when log record header wraps log end
commit 284f1c2c9bebf871861184b0e2c40fa921dd380b upstream. The high-level log recovery algorithm consists of two loops that walk the physical log and process log records from the tail to the head. The first loop handles the case where the tail is beyond the head and processes records up to the end of the physical log. The subsequent loop processes records from the beginning of the physical log to the head. Because log records can wrap around the end of the physical log, the first loop mentioned above must handle this case appropriately. Records are processed from in-core buffers, which means that this algorithm must split the reads of such records into two partial I/Os: 1.) from the beginning of the record to the end of the log and 2.) from the beginning of the log to the end of the record. This is further complicated by the fact that the log record header and log record data are read into independent buffers. The current handling of each buffer correctly splits the reads when either the header or data starts before the end of the log and wraps around the end. The data read does not correctly handle the case where the prior header read wrapped or ends on the physical log end boundary. blk_no is incremented to or beyond the log end after the header read to point to the record data, but the split data read logic triggers, attempts to read from an invalid log block and ultimately causes log recovery to fail. This can be reproduced fairly reliably via xfstests tests generic/047 and generic/388 with large iclog sizes (256k) and small (10M) logs. If the record header read has pushed beyond the end of the physical log, the subsequent data read is actually contiguous. Update the data read logic to detect the case where blk_no has wrapped, mod it against the log size to read from the correct address and issue one contiguous read for the log data buffer. The log record is processed as normal from the buffer(s), the loop exits after the current iteration and the subsequent loop picks up with the first new record after the start of the log. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/xfs/xfs_log_recover.c18
1 files changed, 14 insertions, 4 deletions
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index e06aa2827ecb..9cef8916314a 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -5216,7 +5216,7 @@ xlog_do_recovery_pass(
xfs_daddr_t *first_bad) /* out: first bad log rec */
{
xlog_rec_header_t *rhead;
- xfs_daddr_t blk_no;
+ xfs_daddr_t blk_no, rblk_no;
xfs_daddr_t rhead_blk;
char *offset;
xfs_buf_t *hbp, *dbp;
@@ -5369,9 +5369,19 @@ xlog_do_recovery_pass(
bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
blk_no += hblks;
- /* Read in data for log record */
- if (blk_no + bblks <= log->l_logBBsize) {
- error = xlog_bread(log, blk_no, bblks, dbp,
+ /*
+ * Read the log record data in multiple reads if it
+ * wraps around the end of the log. Note that if the
+ * header already wrapped, blk_no could point past the
+ * end of the log. The record data is contiguous in
+ * that case.
+ */
+ if (blk_no + bblks <= log->l_logBBsize ||
+ blk_no >= log->l_logBBsize) {
+ /* mod blk_no in case the header wrapped and
+ * pushed it beyond the end of the log */
+ rblk_no = do_mod(blk_no, log->l_logBBsize);
+ error = xlog_bread(log, rblk_no, bblks, dbp,
&offset);
if (error)
goto bread_err2;