xfs: recovery of swap extents operations for CRC filesystems

This is the recovery side of the btree block owner change operation
performed by swapext on CRC enabled filesystems. We detect that an
owner change is needed by the flag that has been placed on the inode
log format flag field. Because the inode recovery is being replayed
after the buffers that make up the BMBT in the given checkpoint, we
can walk all the buffers and directly modify them when we see the
flag set on an inode.

Because the inode can be relogged and hence present in multiple
chekpoints with the "change owner" flag set, we could do multiple
passes across the inode to do this change. While this isn't optimal,
we can't directly ignore the flag as there may be multiple
independent swap extent operations being replayed on the same inode
in different checkpoints so we can't ignore them.

Further, because the owner change operation uses ordered buffers, we
might have buffers that are newer on disk than the current
checkpoint and so already have the owner changed in them. Hence we
cannot just peek at a buffer in the tree and check that it has the
correct owner and assume that the change was completed.

So, for the moment just brute force the owner change every time we
see an inode with the flag set. Note that we have to be careful here
because the owner of the buffers may point to either the old owner
or the new owner. Currently the verifier can't verify the owner
directly, so there is no failure case here right now. If we verify
the owner exactly in future, then we'll have to take this into
account.

This was tested in terms of normal operation via xfstests - all of
the fsr tests now pass without failure. however, we really need to
modify xfs/227 to stress v3 inodes correctly to ensure we fully
cover this case for v5 filesystems.

In terms of recovery testing, I used a hacked version of xfs_fsr
that held the temp inode open for a few seconds before exiting so
that the filesystem could be shut down with an open owner change
recovery flags set on at least the temp inode. fsr leaves the temp
inode unlinked and in btree format, so this was necessary for the
owner change to be reliably replayed.

logprint confirmed the tmp inode in the log had the correct flag set:

INO: cnt:3 total:3 a:0x69e9e0 len:56 a:0x69ea20 len:176 a:0x69eae0 len:88
        INODE: #regs:3   ino:0x44  flags:0x209   dsize:88
	                                 ^^^^^

0x200 is set, indicating a data fork owner change needed to be
replayed on inode 0x44.  A printk in the revoery code confirmed that
the inode change was recovered:

XFS (vdc): Mounting Filesystem
XFS (vdc): Starting recovery (logdev: internal)
recovering owner change ino 0x44
XFS (vdc): Version 5 superblock detected. This kernel L support enabled!
Use of these features in this kernel is at your own risk!
XFS (vdc): Ending recovery (logdev: internal)

The script used to test this was:

$ cat ./recovery-fsr.sh
#!/bin/bash

dev=/dev/vdc
mntpt=/mnt/scratch
testfile=$mntpt/testfile

umount $mntpt
mkfs.xfs -f -m crc=1 $dev
mount $dev $mntpt
chmod 777 $mntpt

for i in `seq 10000 -1 0`; do
        xfs_io -f -d -c "pwrite $(($i * 4096)) 4096" $testfile > /dev/null 2>&1
done
xfs_bmap -vp $testfile |head -20

xfs_fsr -d -v $testfile &
sleep 10
/home/dave/src/xfstests-dev/src/godown -f $mntpt
wait
umount $mntpt

xfs_logprint -t $dev |tail -20
time mount $dev $mntpt
xfs_bmap -vp $testfile
umount $mntpt
$

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 99 insertions, 24 deletions

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 1728c7c..1c3b0c9 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -2629,6 +2629,82 @@ out_release:
 	return error;
 }
 
+/*
+ * Inode fork owner changes
+ *
+ * If we have been told that we have to reparent the inode fork, it's because an
+ * extent swap operation on a CRC enabled filesystem has been done and we are
+ * replaying it. We need to walk the BMBT of the appropriate fork and change the
+ * owners of it.
+ *
+ * The complexity here is that we don't have an inode context to work with, so
+ * after we've replayed the inode we need to instantiate one.  This is where the
+ * fun begins.
+ *
+ * We are in the middle of log recovery, so we can't run transactions. That
+ * means we cannot use cache coherent inode instantiation via xfs_iget(), as
+ * that will result in the corresponding iput() running the inode through
+ * xfs_inactive(). If we've just replayed an inode core that changes the link
+ * count to zero (i.e. it's been unlinked), then xfs_inactive() will run
+ * transactions (bad!).
+ *
+ * So, to avoid this, we instantiate an inode directly from the inode core we've
+ * just recovered. We have the buffer still locked, and all we really need to
+ * instantiate is the inode core and the forks being modified. We can do this
+ * manually, then run the inode btree owner change, and then tear down the
+ * xfs_inode without having to run any transactions at all.
+ *
+ * Also, because we don't have a transaction context available here but need to
+ * gather all the buffers we modify for writeback so we pass the buffer_list
+ * instead for the operation to use.
+ */
+
+STATIC int
+xfs_recover_inode_owner_change(
+	struct xfs_mount	*mp,
+	struct xfs_dinode	*dip,
+	struct xfs_inode_log_format *in_f,
+	struct list_head	*buffer_list)
+{
+	struct xfs_inode	*ip;
+	int			error;
+
+	ASSERT(in_f->ilf_fields & (XFS_ILOG_DOWNER|XFS_ILOG_AOWNER));
+
+	ip = xfs_inode_alloc(mp, in_f->ilf_ino);
+	if (!ip)
+		return ENOMEM;
+
+	/* instantiate the inode */
+	xfs_dinode_from_disk(&ip->i_d, dip);
+	ASSERT(ip->i_d.di_version >= 3);
+
+	error = xfs_iformat_fork(ip, dip);
+	if (error)
+		goto out_free_ip;
+
+
+	if (in_f->ilf_fields & XFS_ILOG_DOWNER) {
+		ASSERT(in_f->ilf_fields & XFS_ILOG_DBROOT);
+		error = xfs_bmbt_change_owner(NULL, ip, XFS_DATA_FORK,
+					      ip->i_ino, buffer_list);
+		if (error)
+			goto out_free_ip;
+	}
+
+	if (in_f->ilf_fields & XFS_ILOG_AOWNER) {
+		ASSERT(in_f->ilf_fields & XFS_ILOG_ABROOT);
+		error = xfs_bmbt_change_owner(NULL, ip, XFS_ATTR_FORK,
+					      ip->i_ino, buffer_list);
+		if (error)
+			goto out_free_ip;
+	}
+
+out_free_ip:
+	xfs_inode_free(ip);
+	return error;
+}
+
 STATIC int
 xlog_recover_inode_pass2(
 	struct xlog			*log,
@@ -2681,8 +2757,7 @@ xlog_recover_inode_pass2(
 	error = bp->b_error;
 	if (error) {
 		xfs_buf_ioerror_alert(bp, "xlog_recover_do..(read#2)");
-		xfs_buf_relse(bp);
-		goto error;
+		goto out_release;
 	}
 	ASSERT(in_f->ilf_fields & XFS_ILOG_CORE);
 	dip = (xfs_dinode_t *)xfs_buf_offset(bp, in_f->ilf_boffset);
@@ -2692,30 +2767,31 @@ xlog_recover_inode_pass2(
 	 * like an inode!
 	 */
 	if (unlikely(dip->di_magic != cpu_to_be16(XFS_DINODE_MAGIC))) {
-		xfs_buf_relse(bp);
 		xfs_alert(mp,
 	"%s: Bad inode magic number, dip = 0x%p, dino bp = 0x%p, ino = %Ld",
 			__func__, dip, bp, in_f->ilf_ino);
 		XFS_ERROR_REPORT("xlog_recover_inode_pass2(1)",
 				 XFS_ERRLEVEL_LOW, mp);
 		error = EFSCORRUPTED;
-		goto error;
+		goto out_release;
 	}
 	dicp = item->ri_buf[1].i_addr;
 	if (unlikely(dicp->di_magic != XFS_DINODE_MAGIC)) {
-		xfs_buf_relse(bp);
 		xfs_alert(mp,
 			"%s: Bad inode log record, rec ptr 0x%p, ino %Ld",
 			__func__, item, in_f->ilf_ino);
 		XFS_ERROR_REPORT("xlog_recover_inode_pass2(2)",
 				 XFS_ERRLEVEL_LOW, mp);
 		error = EFSCORRUPTED;
-		goto error;
+		goto out_release;
 	}
 
 	/*
 	 * If the inode has an LSN in it, recover the inode only if it's less
-	 * than the lsn of the transaction we are replaying.
+	 * than the lsn of the transaction we are replaying. Note: we still
+	 * need to replay an owner change even though the inode is more recent
+	 * than the transaction as there is no guarantee that all the btree
+	 * blocks are more recent than this transaction, too.
 	 */
 	if (dip->di_version >= 3) {
 		xfs_lsn_t	lsn = be64_to_cpu(dip->di_lsn);
@@ -2723,7 +2799,7 @@ xlog_recover_inode_pass2(
 		if (lsn && lsn != -1 && XFS_LSN_CMP(lsn, current_lsn) >= 0) {
 			trace_xfs_log_recover_inode_skip(log, in_f);
 			error = 0;
-			goto out_release;
+			goto out_owner_change;
 		}
 	}
 
@@ -2745,10 +2821,9 @@ xlog_recover_inode_pass2(
 		    dicp->di_flushiter < (DI_MAX_FLUSH >> 1)) {
 			/* do nothing */
 		} else {
-			xfs_buf_relse(bp);
 			trace_xfs_log_recover_inode_skip(log, in_f);
 			error = 0;
-			goto error;
+			goto out_release;
 		}
 	}
 
@@ -2760,13 +2835,12 @@ xlog_recover_inode_pass2(
 		    (dicp->di_format != XFS_DINODE_FMT_BTREE)) {
 			XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(3)",
 					 XFS_ERRLEVEL_LOW, mp, dicp);
-			xfs_buf_relse(bp);
 			xfs_alert(mp,
 		"%s: Bad regular inode log record, rec ptr 0x%p, "
 		"ino ptr = 0x%p, ino bp = 0x%p, ino %Ld",
 				__func__, item, dip, bp, in_f->ilf_ino);
 			error = EFSCORRUPTED;
-			goto error;
+			goto out_release;
 		}
 	} else if (unlikely(S_ISDIR(dicp->di_mode))) {
 		if ((dicp->di_format != XFS_DINODE_FMT_EXTENTS) &&
@@ -2774,19 +2848,17 @@ xlog_recover_inode_pass2(
 		    (dicp->di_format != XFS_DINODE_FMT_LOCAL)) {
 			XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(4)",
 					     XFS_ERRLEVEL_LOW, mp, dicp);
-			xfs_buf_relse(bp);
 			xfs_alert(mp,
 		"%s: Bad dir inode log record, rec ptr 0x%p, "
 		"ino ptr = 0x%p, ino bp = 0x%p, ino %Ld",
 				__func__, item, dip, bp, in_f->ilf_ino);
 			error = EFSCORRUPTED;
-			goto error;
+			goto out_release;
 		}
 	}
 	if (unlikely(dicp->di_nextents + dicp->di_anextents > dicp->di_nblocks)){
 		XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(5)",
 				     XFS_ERRLEVEL_LOW, mp, dicp);
-		xfs_buf_relse(bp);
 		xfs_alert(mp,
 	"%s: Bad inode log record, rec ptr 0x%p, dino ptr 0x%p, "
 	"dino bp 0x%p, ino %Ld, total extents = %d, nblocks = %Ld",
@@ -2794,29 +2866,27 @@ xlog_recover_inode_pass2(
 			dicp->di_nextents + dicp->di_anextents,
 			dicp->di_nblocks);
 		error = EFSCORRUPTED;
-		goto error;
+		goto out_release;
 	}
 	if (unlikely(dicp->di_forkoff > mp->m_sb.sb_inodesize)) {
 		XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(6)",
 				     XFS_ERRLEVEL_LOW, mp, dicp);
-		xfs_buf_relse(bp);
 		xfs_alert(mp,
 	"%s: Bad inode log record, rec ptr 0x%p, dino ptr 0x%p, "
 	"dino bp 0x%p, ino %Ld, forkoff 0x%x", __func__,
 			item, dip, bp, in_f->ilf_ino, dicp->di_forkoff);
 		error = EFSCORRUPTED;
-		goto error;
+		goto out_release;
 	}
 	isize = xfs_icdinode_size(dicp->di_version);
 	if (unlikely(item->ri_buf[1].i_len > isize)) {
 		XFS_CORRUPTION_ERROR("xlog_recover_inode_pass2(7)",
 				     XFS_ERRLEVEL_LOW, mp, dicp);
-		xfs_buf_relse(bp);
 		xfs_alert(mp,
 			"%s: Bad inode log record length %d, rec ptr 0x%p",
 			__func__, item->ri_buf[1].i_len, item);
 		error = EFSCORRUPTED;
-		goto error;
+		goto out_release;
 	}
 
 	/* The core is in in-core format */
@@ -2842,7 +2912,7 @@ xlog_recover_inode_pass2(
 	}
 
 	if (in_f->ilf_size == 2)
-		goto write_inode_buffer;
+		goto out_owner_change;
 	len = item->ri_buf[2].i_len;
 	src = item->ri_buf[2].i_addr;
 	ASSERT(in_f->ilf_size <= 4);
@@ -2903,13 +2973,15 @@ xlog_recover_inode_pass2(
 		default:
 			xfs_warn(log->l_mp, "%s: Invalid flag", __func__);
 			ASSERT(0);
-			xfs_buf_relse(bp);
 			error = EIO;
-			goto error;
+			goto out_release;
 		}
 	}
 
-write_inode_buffer:
+out_owner_change:
+	if (in_f->ilf_fields & (XFS_ILOG_DOWNER|XFS_ILOG_AOWNER))
+		error = xfs_recover_inode_owner_change(mp, dip, in_f,
+						       buffer_list);
 	/* re-generate the checksum. */
 	xfs_dinode_calc_crc(log->l_mp, dip);
 
@@ -2923,6 +2995,9 @@ error:
 	if (need_free)
 		kmem_free(in_f);
 	return XFS_ERROR(error);
+
+	xfs_buf_relse(bp);
+	goto error;
 }
 
 /*