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author | mckusick <mckusick@FreeBSD.org> | 2003-11-04 07:34:32 +0000 |
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committer | mckusick <mckusick@FreeBSD.org> | 2003-11-04 07:34:32 +0000 |
commit | f692f640895d645706322a61176089c98dee8fb2 (patch) | |
tree | 6f3aa13f518b935b5b70ee59a98ad4ad352cc8ac /sbin/newfs/mkfs.c | |
parent | 8cecbe74983913d60c797d1c6082e062de4b3b13 (diff) | |
download | FreeBSD-src-f692f640895d645706322a61176089c98dee8fb2.zip FreeBSD-src-f692f640895d645706322a61176089c98dee8fb2.tar.gz |
Create a .snap directory mode 770 group operator in the root of
a new filesystem. Dump and fsck will create snapshots in this
directory rather than in the root for two reasons:
1) For terabyte-sized filesystems, the snapshot may require many
minutes to build. Although the filesystem will not be suspended
during most of the snapshot build, the snapshot file itself is
locked during the entire snapshot build period. Thus, if it is
accessed during the period that it is being built, the process
trying to access it will block holding its containing directory
locked. If the snapshot is in the root, the root will lock and
the system will come to a halt until the snapshot finishes. By
putting the snapshot in a subdirectory, it is out of the likely
path of any process traversing through the root and hence much
less likely to cause a lock race to the root.
2) The dump program is usually run by a non-root user running with
operator group privilege. Such a user is typically not permitted
to create files in the root of a filesystem. By having a directory
in group operator with group write access available, such a user
will be able to create a snapshot there. Having the dump program
create its snapshot in a subdirectory below the root will benefit
from point (1) as well.
Sponsored by: DARPA & NAI Labs.
Diffstat (limited to 'sbin/newfs/mkfs.c')
-rw-r--r-- | sbin/newfs/mkfs.c | 51 |
1 files changed, 45 insertions, 6 deletions
diff --git a/sbin/newfs/mkfs.c b/sbin/newfs/mkfs.c index 80ed645..1c117e6 100644 --- a/sbin/newfs/mkfs.c +++ b/sbin/newfs/mkfs.c @@ -49,6 +49,7 @@ static char sccsid[] = "@(#)mkfs.c 8.11 (Berkeley) 5/3/95"; __FBSDID("$FreeBSD$"); #include <err.h> +#include <grp.h> #include <limits.h> #include <signal.h> #include <stdlib.h> @@ -700,19 +701,30 @@ initcg(int cylno, time_t utime) /* * initialize the file system */ -#define PREDEFDIR 2 +#define ROOTLINKCNT 3 struct direct root_dir[] = { { ROOTINO, sizeof(struct direct), DT_DIR, 1, "." }, { ROOTINO, sizeof(struct direct), DT_DIR, 2, ".." }, + { ROOTINO + 1, sizeof(struct direct), DT_DIR, 5, ".snap" }, +}; + +#define SNAPLINKCNT 2 + +struct direct snap_dir[] = { + { ROOTINO + 1, sizeof(struct direct), DT_DIR, 1, "." }, + { ROOTINO, sizeof(struct direct), DT_DIR, 2, ".." }, }; void fsinit(time_t utime) { union dinode node; + struct group *grp; memset(&node, 0, sizeof node); + if ((grp = getgrnam("operator")) == NULL) + errx(35, "Cannot retrieve operator gid"); if (sblock.fs_magic == FS_UFS1_MAGIC) { /* * initialize the node @@ -724,13 +736,27 @@ fsinit(time_t utime) * create the root directory */ node.dp1.di_mode = IFDIR | UMASK; - node.dp1.di_nlink = PREDEFDIR; - node.dp1.di_size = makedir(root_dir, PREDEFDIR); + node.dp1.di_nlink = ROOTLINKCNT; + node.dp1.di_size = makedir(root_dir, ROOTLINKCNT); + node.dp1.di_db[0] = alloc(sblock.fs_fsize, node.dp1.di_mode); + node.dp1.di_blocks = + btodb(fragroundup(&sblock, node.dp1.di_size)); + wtfs(fsbtodb(&sblock, node.dp1.di_db[0]), sblock.fs_fsize, + iobuf); + iput(&node, ROOTINO); + /* + * create the .snap directory + */ + node.dp1.di_mode |= 020; + node.dp1.di_gid = grp->gr_gid; + node.dp1.di_nlink = SNAPLINKCNT; + node.dp1.di_size = makedir(snap_dir, SNAPLINKCNT); node.dp1.di_db[0] = alloc(sblock.fs_fsize, node.dp1.di_mode); node.dp1.di_blocks = btodb(fragroundup(&sblock, node.dp1.di_size)); wtfs(fsbtodb(&sblock, node.dp1.di_db[0]), sblock.fs_fsize, iobuf); + iput(&node, ROOTINO + 1); } else { /* * initialize the node @@ -743,15 +769,28 @@ fsinit(time_t utime) * create the root directory */ node.dp2.di_mode = IFDIR | UMASK; - node.dp2.di_nlink = PREDEFDIR; - node.dp2.di_size = makedir(root_dir, PREDEFDIR); + node.dp2.di_nlink = ROOTLINKCNT; + node.dp2.di_size = makedir(root_dir, ROOTLINKCNT); + node.dp2.di_db[0] = alloc(sblock.fs_fsize, node.dp2.di_mode); + node.dp2.di_blocks = + btodb(fragroundup(&sblock, node.dp2.di_size)); + wtfs(fsbtodb(&sblock, node.dp2.di_db[0]), sblock.fs_fsize, + iobuf); + iput(&node, ROOTINO); + /* + * create the .snap directory + */ + node.dp2.di_mode |= 020; + node.dp2.di_gid = grp->gr_gid; + node.dp2.di_nlink = SNAPLINKCNT; + node.dp2.di_size = makedir(snap_dir, SNAPLINKCNT); node.dp2.di_db[0] = alloc(sblock.fs_fsize, node.dp2.di_mode); node.dp2.di_blocks = btodb(fragroundup(&sblock, node.dp2.di_size)); wtfs(fsbtodb(&sblock, node.dp2.di_db[0]), sblock.fs_fsize, iobuf); + iput(&node, ROOTINO + 1); } - iput(&node, ROOTINO); } /* |