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authorKirk McKusick <mckusick@FreeBSD.org>2018-12-06 00:09:39 +0000
committerKirk McKusick <mckusick@FreeBSD.org>2018-12-06 00:09:39 +0000
commitfb14e73cb4062d7272ce6183d748adedd868906b (patch)
tree5f7d25721fa794a719544a1967b6c9d511f59d69 /sys/ufs/ffs/ffs_subr.c
parent369d9a2c153e45e2645bc78cdc3a8cdc42f45b7b (diff)
downloadsrc-fb14e73cb4062d7272ce6183d748adedd868906b.tar.gz
src-fb14e73cb4062d7272ce6183d748adedd868906b.zip
Normally when an attempt is made to mount a UFS/FFS filesystem whose
superblock has a check-hash error, an error message noting the superblock check-hash failure is printed and the mount fails. The administrator then runs fsck to repair the filesystem and when successful, the filesystem can once again be mounted. This approach fails if the filesystem in question is a root filesystem from which you are trying to boot. Here, the loader fails when trying to access the filesystem to get the kernel to boot. So it is necessary to allow the loader to ignore the superblock check-hash error and make a best effort to read the kernel. The filesystem may be suffiently corrupted that the read attempt fails, but there is no harm in trying since the loader makes no attempt to write to the filesystem. Once the kernel is loaded and starts to run, it attempts to mount its root filesystem. Once again, failure means that it breaks to its prompt to ask where to get its root filesystem. Unless you have an alternate root filesystem, you are stuck. Since the root filesystem is initially mounted read-only, it is safe to make an attempt to mount the root filesystem with the failed superblock check-hash. Thus, when asked to mount a root filesystem with a failed superblock check-hash, the kernel prints a warning message that the root filesystem superblock check-hash needs repair, but notes that it is ignoring the error and proceeding. It does mark the filesystem as needing an fsck which prevents it from being enabled for writing until fsck has been run on it. The net effect is that the reboot fails to single user, but at least at that point the administrator has the tools at hand to fix the problem. Reported by: Rick Macklem (rmacklem@) Discussed with: Warner Losh (imp@) Sponsored by: Netflix
Notes
Notes: svn path=/head/; revision=341608
Diffstat (limited to 'sys/ufs/ffs/ffs_subr.c')
-rw-r--r--sys/ufs/ffs/ffs_subr.c35
1 files changed, 26 insertions, 9 deletions
diff --git a/sys/ufs/ffs/ffs_subr.c b/sys/ufs/ffs/ffs_subr.c
index e4dbd730b186..64354bbd5383 100644
--- a/sys/ufs/ffs/ffs_subr.c
+++ b/sys/ufs/ffs/ffs_subr.c
@@ -51,6 +51,11 @@ struct malloc_type;
#define UFS_MALLOC(size, type, flags) malloc(size)
#define UFS_FREE(ptr, type) free(ptr)
#define UFS_TIME time(NULL)
+/*
+ * Request standard superblock location in ffs_sbget
+ */
+#define STDSB -1 /* Fail if check-hash is bad */
+#define STDSB_NOHASHFAIL -2 /* Ignore check-hash failure */
#else /* _KERNEL */
#include <sys/systm.h>
@@ -139,14 +144,14 @@ ffs_load_inode(struct buf *bp, struct inode *ip, struct fs *fs, ino_t ino)
ip->i_gid = dip2->di_gid;
return (0);
}
-#endif /* KERNEL */
+#endif /* _KERNEL */
/*
* These are the low-level functions that actually read and write
* the superblock and its associated data.
*/
static off_t sblock_try[] = SBLOCKSEARCH;
-static int readsuper(void *, struct fs **, off_t, int,
+static int readsuper(void *, struct fs **, off_t, int, int,
int (*)(void *, off_t, void **, int));
/*
@@ -177,21 +182,25 @@ ffs_sbget(void *devfd, struct fs **fsp, off_t altsblock,
int i, error, size, blks;
uint8_t *space;
int32_t *lp;
+ int chkhash;
char *buf;
fs = NULL;
*fsp = NULL;
- if (altsblock != -1) {
- if ((error = readsuper(devfd, &fs, altsblock, 1,
+ chkhash = 1;
+ if (altsblock >= 0) {
+ if ((error = readsuper(devfd, &fs, altsblock, 1, chkhash,
readfunc)) != 0) {
if (fs != NULL)
UFS_FREE(fs, filltype);
return (error);
}
} else {
+ if (altsblock == STDSB_NOHASHFAIL)
+ chkhash = 0;
for (i = 0; sblock_try[i] != -1; i++) {
if ((error = readsuper(devfd, &fs, sblock_try[i], 0,
- readfunc)) == 0)
+ chkhash, readfunc)) == 0)
break;
if (fs != NULL) {
UFS_FREE(fs, filltype);
@@ -255,7 +264,7 @@ ffs_sbget(void *devfd, struct fs **fsp, off_t altsblock,
*/
static int
readsuper(void *devfd, struct fs **fsp, off_t sblockloc, int isaltsblk,
- int (*readfunc)(void *devfd, off_t loc, void **bufp, int size))
+ int chkhash, int (*readfunc)(void *devfd, off_t loc, void **bufp, int size))
{
struct fs *fs;
int error, res;
@@ -285,8 +294,9 @@ readsuper(void *devfd, struct fs **fsp, off_t sblockloc, int isaltsblk,
if (fs->fs_ckhash != (ckhash = ffs_calc_sbhash(fs))) {
#ifdef _KERNEL
res = uprintf("Superblock check-hash failed: recorded "
- "check-hash 0x%x != computed check-hash 0x%x\n",
- fs->fs_ckhash, ckhash);
+ "check-hash 0x%x != computed check-hash 0x%x%s\n",
+ fs->fs_ckhash, ckhash,
+ chkhash == 0 ? " (Ignored)" : "");
#else
res = 0;
#endif
@@ -297,7 +307,14 @@ readsuper(void *devfd, struct fs **fsp, off_t sblockloc, int isaltsblk,
if (res == 0)
printf("Superblock check-hash failed: recorded "
"check-hash 0x%x != computed check-hash "
- "0x%x\n", fs->fs_ckhash, ckhash);
+ "0x%x%s\n", fs->fs_ckhash, ckhash,
+ chkhash == 0 ? " (Ignored)" : "");
+ if (chkhash == 0) {
+ fs->fs_flags |= FS_NEEDSFSCK;
+ fs->fs_fmod = 1;
+ return (0);
+ }
+ fs->fs_fmod = 0;
return (EINVAL);
}
/* Have to set for old filesystems that predate this field */