git: 5c6b3e4b5dfa - stable/13 - Eliminate snaplk / bufwait LOR when creating UFS snapshots

[Kirk McKusick]

The branch stable/13 has been updated by mckusick:

URL: https://cgit.FreeBSD.org/src/commit/?id=5c6b3e4b5dfa554e7e6eb246481e654402de1ca0

commit 5c6b3e4b5dfa554e7e6eb246481e654402de1ca0
Author:     Kirk McKusick <mckusick at FreeBSD.org>
AuthorDate: 2021-09-18 23:51:07 +0000
Commit:     Kirk McKusick <mckusick at FreeBSD.org>
CommitDate: 2021-09-28 03:13:38 +0000

    Eliminate snaplk / bufwait LOR when creating UFS snapshots
    
    (cherry picked from commit d7770a5495b19a987dddc77cabcdeadf18413b4d)
---
 sys/ufs/ffs/ffs_snapshot.c | 42 +++++++++++++++++++++---------------------
 1 file changed, 21 insertions(+), 21 deletions(-)

diff --git a/sys/ufs/ffs/ffs_snapshot.c b/sys/ufs/ffs/ffs_snapshot.c
index 6da84fb46bb0..baad50cab2ba 100644
--- a/sys/ufs/ffs/ffs_snapshot.c
+++ b/sys/ufs/ffs/ffs_snapshot.c
@@ -650,6 +650,27 @@ loop:
 			    BLK_NOCOPY, 0);
 		vput(xvp);
 	}
+	/*
+	 * Preallocate all the direct blocks in the snapshot inode so
+	 * that we never have to write the inode itself to commit an
+	 * update to the contents of the snapshot. Note that once
+	 * created, the size of the snapshot will never change, so
+	 * there will never be a need to write the inode except to
+	 * update the non-integrity-critical time fields and
+	 * allocated-block count.
+	 */
+	for (blockno = 0; blockno < UFS_NDADDR; blockno++) {
+		if (DIP(ip, i_db[blockno]) != 0)
+			continue;
+		error = UFS_BALLOC(vp, lblktosize(fs, blockno),
+		    fs->fs_bsize, KERNCRED, BA_CLRBUF, &bp);
+		if (error)
+			goto resumefs;
+		error = readblock(vp, bp, blockno);
+		bawrite(bp);
+		if (error != 0)
+			goto resumefs;
+	}
 	/*
 	 * Acquire a lock on the snapdata structure, creating it if necessary.
 	 */
@@ -691,27 +712,6 @@ loop:
 		sn->sn_listsize = blkp - snapblklist;
 		VI_UNLOCK(devvp);
 	}
-	/*
-	 * Preallocate all the direct blocks in the snapshot inode so
-	 * that we never have to write the inode itself to commit an
-	 * update to the contents of the snapshot. Note that once
-	 * created, the size of the snapshot will never change, so
-	 * there will never be a need to write the inode except to
-	 * update the non-integrity-critical time fields and
-	 * allocated-block count.
-	 */
-	for (blockno = 0; blockno < UFS_NDADDR; blockno++) {
-		if (DIP(ip, i_db[blockno]) != 0)
-			continue;
-		error = UFS_BALLOC(vp, lblktosize(fs, blockno),
-		    fs->fs_bsize, KERNCRED, BA_CLRBUF, &bp);
-		if (error)
-			goto resumefs;
-		error = readblock(vp, bp, blockno);
-		bawrite(bp);
-		if (error != 0)
-			goto resumefs;
-	}
 	/*
 	 * Record snapshot inode. Since this is the newest snapshot,
 	 * it must be placed at the end of the list.