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authordes <des@FreeBSD.org>2009-09-25 18:44:34 +0000
committerdes <des@FreeBSD.org>2009-09-25 18:44:34 +0000
commit2c6fa42d07734255d2c09e632f839efcd6534564 (patch)
treec919fc350655cd99b7ddbd065bcf005d54d4cfec /sys/ufs
parent9ed1a4b5ebe734049aa444f14884ed8ad4c23aee (diff)
downloadFreeBSD-src-2c6fa42d07734255d2c09e632f839efcd6534564.zip
FreeBSD-src-2c6fa42d07734255d2c09e632f839efcd6534564.tar.gz
Improve comments, and remove a bogus 0 id check.
Diffstat (limited to 'sys/ufs')
-rw-r--r--sys/ufs/ufs/ufs_quota.c51
1 files changed, 35 insertions, 16 deletions
diff --git a/sys/ufs/ufs/ufs_quota.c b/sys/ufs/ufs/ufs_quota.c
index ddba601..04d28e4 100644
--- a/sys/ufs/ufs/ufs_quota.c
+++ b/sys/ufs/ufs/ufs_quota.c
@@ -60,6 +60,8 @@ __FBSDID("$FreeBSD$");
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/ufs_extern.h>
+CTASSERT(sizeof(struct dqblk64) == sizeof(struct dqhdr64));
+
static int unprivileged_get_quota = 0;
SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_get_quota, CTLFLAG_RW,
&unprivileged_get_quota, 0,
@@ -1124,6 +1126,14 @@ dqhashfind(struct dqhash *dqh, u_long id, struct vnode *dqvp)
/*
* Determine the quota file type.
+ *
+ * A 32-bit quota file is simply an array of struct dqblk32.
+ *
+ * A 64-bit quota file is a struct dqhdr64 followed by an array of struct
+ * dqblk64. The header contains various magic bits which allow us to be
+ * reasonably confident that it is indeeda 64-bit quota file and not just
+ * a 32-bit quota file that just happens to "look right".
+ *
*/
static int
dqopen(struct vnode *vp, struct ufsmount *ump, int type)
@@ -1312,23 +1322,8 @@ hfound: DQI_LOCK(dq);
/*
* Read the requested quota record from the quota file, performing
* any necessary conversions.
- *
- * The record's offset within the file depends on the size of the
- * record, which means we need to know whether it's a 32-bit file
- * or a 64-bit file.
- *
- * Luckily, root's record is always at offset 0, and most of it is
- * unused, so we can use it to store a magic number indicating the
- * file format. Due to an acute lack of imagination, this magic
- * number, stored in the first byte of root's record and hence the
- * first byte of the file, is 64.
- *
- * Another lucky break is that quotaon() always loads root's
- * record, to get the default values for dq_btime and dq_itime, so
- * we will always have a chance to check the file format before
- * being asked for a "real" record.
*/
- if (id == 0 || (ump->um_qflags[type] & QTF_64BIT)) {
+ if (ump->um_qflags[type] & QTF_64BIT) {
recsize = sizeof(struct dqblk64);
base = sizeof(struct dqhdr64);
} else {
@@ -1597,6 +1592,10 @@ dqflush(struct vnode *vp)
#define CLIP32(u64) (u64 > UINT32_MAX ? UINT32_MAX : (uint32_t)u64)
+/*
+ * Convert on-disk 32-bit host-order structure to in-memory 64-bit
+ * host-order structure.
+ */
static void
dqb32_dq(const struct dqblk32 *dqb32, struct dquot *dq)
{
@@ -1611,6 +1610,10 @@ dqb32_dq(const struct dqblk32 *dqb32, struct dquot *dq)
dq->dq_itime = dqb32->dqb_itime;
}
+/*
+ * Convert on-disk 64-bit network-order structure to in-memory 64-bit
+ * host-order structure.
+ */
static void
dqb64_dq(const struct dqblk64 *dqb64, struct dquot *dq)
{
@@ -1625,6 +1628,10 @@ dqb64_dq(const struct dqblk64 *dqb64, struct dquot *dq)
dq->dq_itime = be64toh(dqb64->dqb_itime);
}
+/*
+ * Convert in-memory 64-bit host-order structure to on-disk 32-bit
+ * host-order structure.
+ */
static void
dq_dqb32(const struct dquot *dq, struct dqblk32 *dqb32)
{
@@ -1639,6 +1646,10 @@ dq_dqb32(const struct dquot *dq, struct dqblk32 *dqb32)
dqb32->dqb_itime = CLIP32(dq->dq_itime);
}
+/*
+ * Convert in-memory host-order 64-bit structure to on-disk 64-bit
+ * network-order structure.
+ */
static void
dq_dqb64(const struct dquot *dq, struct dqblk64 *dqb64)
{
@@ -1653,6 +1664,10 @@ dq_dqb64(const struct dquot *dq, struct dqblk64 *dqb64)
dqb64->dqb_itime = htobe64(dq->dq_itime);
}
+/*
+ * Convert in-memory 64-bit host-order structure to in-memory 32-bit
+ * host-order structure.
+ */
static void
dqb64_dqb32(const struct dqblk64 *dqb64, struct dqblk32 *dqb32)
{
@@ -1667,6 +1682,10 @@ dqb64_dqb32(const struct dqblk64 *dqb64, struct dqblk32 *dqb32)
dqb32->dqb_itime = CLIP32(dqb64->dqb_itime);
}
+/*
+ * Convert in-memory 32-bit host-order structure to in-memory 64-bit
+ * host-order structure.
+ */
static void
dqb32_dqb64(const struct dqblk32 *dqb32, struct dqblk64 *dqb64)
{
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