git: ef20cd33d328 - main - makefs/zfs: Ensure that the last block of a file has the right size

The branch main has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=ef20cd33d3287ebead0d30f2e177fc57a97dc2d5

commit ef20cd33d3287ebead0d30f2e177fc57a97dc2d5
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2023-09-28 20:16:17 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2023-09-28 20:16:17 +0000

    makefs/zfs: Ensure that the last block of a file has the right size
    
    When copying a file's contents into the pool, a loop copies blocks of
    the maximum size (128KB), allocating space from the vdev for each block.
    The space allocator rounds up to the nearest block size, but for files
    larger than the maximum size, this can result in the last block having a
    smaller logical size than the rest of the blocks belonging to that
    dnode.  This violates some ZFS invariants when appending to that file.
    
    Modify fs_populate_file() to use the same block size for the final
    block.
    
    Reported by:    cperciva
    MFC after:      1 week
    Sponsored by:   The FreeBSD Foundation
---
 usr.sbin/makefs/zfs/fs.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/usr.sbin/makefs/zfs/fs.c b/usr.sbin/makefs/zfs/fs.c
index 0d85ea8eb9d8..b0a4c639f256 100644
--- a/usr.sbin/makefs/zfs/fs.c
+++ b/usr.sbin/makefs/zfs/fs.c
@@ -515,7 +515,7 @@ fs_populate_file(fsnode *cur, struct fs_populate_arg *arg)
 	uint64_t dnid;
 	ssize_t n;
 	size_t bufsz;
-	off_t size, target;
+	off_t nbytes, reqbytes, size;
 	int fd;
 
 	assert(cur->type == S_IFREG);
@@ -546,29 +546,30 @@ fs_populate_file(fsnode *cur, struct fs_populate_arg *arg)
 	bufsz = sizeof(zfs->filebuf);
 	size = cur->inode->st.st_size;
 	c = dnode_cursor_init(zfs, arg->fs->os, dnode, size, 0);
-	for (off_t foff = 0; foff < size; foff += target) {
+	for (off_t foff = 0; foff < size; foff += nbytes) {
 		off_t loc, sofar;
 
 		/*
 		 * Fill up our buffer, handling partial reads.
 		 */
 		sofar = 0;
-		target = MIN(size - foff, (off_t)bufsz);
+		nbytes = MIN(size - foff, (off_t)bufsz);
 		do {
-			n = read(fd, buf + sofar, target);
+			n = read(fd, buf + sofar, nbytes);
 			if (n < 0)
 				err(1, "reading from '%s'", cur->name);
 			if (n == 0)
 				errx(1, "unexpected EOF reading '%s'",
 				    cur->name);
 			sofar += n;
-		} while (sofar < target);
+		} while (sofar < nbytes);
 
-		if (target < (off_t)bufsz)
-			memset(buf + target, 0, bufsz - target);
+		if (nbytes < (off_t)bufsz)
+			memset(buf + nbytes, 0, bufsz - nbytes);
 
-		loc = objset_space_alloc(zfs, arg->fs->os, &target);
-		vdev_pwrite_dnode_indir(zfs, dnode, 0, 1, buf, target, loc,
+		reqbytes = foff == 0 ? nbytes : MAXBLOCKSIZE;
+		loc = objset_space_alloc(zfs, arg->fs->os, &reqbytes);
+		vdev_pwrite_dnode_indir(zfs, dnode, 0, 1, buf, reqbytes, loc,
 		    dnode_cursor_next(zfs, c, foff));
 	}
 	eclose(fd);