Linux 6.6 compat: use inode_get/set_ctime*(...)

In Linux commit 13bc24457850583a2e7203ded05b7209ab4bc5ef, direct access
to the i_ctime member of struct inode was removed. The new approach is
to use accessor methods that exclusively handle passing the timestamp
around by value. This change adds new tests for each of these functions
and introduces zpl_* equivalents in include/os/linux/zfs/sys/zpl.h. In
where the inode_get/set_ctime*() functions exist, these zpl_* calls will
be mapped to the new functions. On older kernels, these macros just wrap
direct-access calls. The code that operated on an address of ip->i_ctime
to call ZFS_TIME_DECODE() now will take a local copy using
zpl_inode_get_ctime(), and then pass the address of the local copy when
performing the ZFS_TIME_DECODE() call, in all cases, rather than
directly accessing the member.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Coleman Kane <ckane@colemankane.org>
Closes openzfs#15263
Closes openzfs#15257

config/kernel-inode-times.m4

@@ -27,6 +27,31 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_TIMES], [
 		memset(&ip, 0, sizeof(ip));
 		ts = ip.i_mtime;
 	])
+
+	dnl #
+	dnl # 6.6 API change
+	dnl # i_ctime no longer directly accessible, must use
+	dnl # inode_get_ctime(ip), inode_set_ctime*(ip) to
+	dnl # read/write.
+	dnl #
+	ZFS_LINUX_TEST_SRC([inode_get_ctime], [
+		#include <linux/fs.h>
+	],[
+		struct inode ip;
+
+		memset(&ip, 0, sizeof(ip));
+		inode_get_ctime(&ip);
+	])
+
+	ZFS_LINUX_TEST_SRC([inode_set_ctime_to_ts], [
+		#include <linux/fs.h>
+	],[
+		struct inode ip;
+		struct timespec64 ts;
+
+		memset(&ip, 0, sizeof(ip));
+		inode_set_ctime_to_ts(&ip, ts);
+	])
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_INODE_TIMES], [
@@ -47,4 +72,22 @@ AC_DEFUN([ZFS_AC_KERNEL_INODE_TIMES], [
 		AC_DEFINE(HAVE_INODE_TIMESPEC64_TIMES, 1,
 		    [inode->i_*time's are timespec64])
 	])
+
+	AC_MSG_CHECKING([whether inode_get_ctime() exists])
+	ZFS_LINUX_TEST_RESULT([inode_get_ctime], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_INODE_GET_CTIME, 1,
+		    [inode_get_ctime() exists in linux/fs.h])
+	],[
+		AC_MSG_RESULT(no)
+	])
+
+	AC_MSG_CHECKING([whether inode_set_ctime_to_ts() exists])
+	ZFS_LINUX_TEST_RESULT([inode_set_ctime_to_ts], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_INODE_SET_CTIME_TO_TS, 1,
+		    [inode_set_ctime_to_ts() exists in linux/fs.h])
+	],[
+		AC_MSG_RESULT(no)
+	])
 ])

include/os/linux/zfs/sys/zpl.h

@@ -263,4 +263,15 @@ extern long zpl_ioctl_fideduperange(struct file *filp, void *arg);
 #define	zpl_setattr_prepare(ns, dentry, ia)	setattr_prepare(dentry, ia)
 #endif
 
+#ifdef HAVE_INODE_GET_CTIME
+#define	zpl_inode_get_ctime(ip)	inode_get_ctime(ip)
+#else
+#define	zpl_inode_get_ctime(ip)	(ip->i_ctime)
+#endif
+#ifdef HAVE_INODE_SET_CTIME_TO_TS
+#define	zpl_inode_set_ctime_to_ts(ip, ts)	inode_set_ctime_to_ts(ip, ts)
+#else
+#define	zpl_inode_set_ctime_to_ts(ip, ts)	(ip->i_ctime = ts)
+#endif
+
 #endif	/* _SYS_ZPL_H */

module/os/linux/zfs/zfs_ctldir.c

@@ -522,7 +522,7 @@ zfsctl_inode_alloc(zfsvfs_t *zfsvfs, uint64_t id,
 	ip->i_blkbits = SPA_MINBLOCKSHIFT;
 	ip->i_atime = now;
 	ip->i_mtime = now;
-	ip->i_ctime = now;
+	zpl_inode_set_ctime_to_ts(ip, now);
 	ip->i_fop = fops;
 	ip->i_op = ops;
 #if defined(IOP_XATTR)

module/os/linux/zfs/zfs_vnops_os.c

@@ -2439,8 +2439,8 @@ zfs_setattr(znode_t *zp, vattr_t *vap, int flags, cred_t *cr, zidmap_t *mnt_ns)
 
 	if (mask & (ATTR_CTIME | ATTR_SIZE)) {
 		ZFS_TIME_ENCODE(&vap->va_ctime, ctime);
-		ZTOI(zp)->i_ctime = zpl_inode_timestamp_truncate(vap->va_ctime,
-		    ZTOI(zp));
+		zpl_inode_set_ctime_to_ts(ZTOI(zp),
+		    zpl_inode_timestamp_truncate(vap->va_ctime, ZTOI(zp)));
 		SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
 		    ctime, sizeof (ctime));
 	}
@@ -3645,6 +3645,7 @@ zfs_putpage(struct inode *ip, struct page *pp, struct writeback_control *wbc,
 	caddr_t		va;
 	int		err = 0;
 	uint64_t	mtime[2], ctime[2];
+	inode_timespec_t tmp_ctime;
 	sa_bulk_attr_t	bulk[3];
 	int		cnt = 0;
 	struct address_space *mapping;
@@ -3809,7 +3810,8 @@ zfs_putpage(struct inode *ip, struct page *pp, struct writeback_control *wbc,
 
 	/* Preserve the mtime and ctime provided by the inode */
 	ZFS_TIME_ENCODE(&ip->i_mtime, mtime);
-	ZFS_TIME_ENCODE(&ip->i_ctime, ctime);
+	tmp_ctime = zpl_inode_get_ctime(ip);
+	ZFS_TIME_ENCODE(&tmp_ctime, ctime);
 	zp->z_atime_dirty = B_FALSE;
 	zp->z_seq++;
 
@@ -3859,6 +3861,7 @@ zfs_dirty_inode(struct inode *ip, int flags)
 	zfsvfs_t	*zfsvfs = ITOZSB(ip);
 	dmu_tx_t	*tx;
 	uint64_t	mode, atime[2], mtime[2], ctime[2];
+	inode_timespec_t tmp_ctime;
 	sa_bulk_attr_t	bulk[4];
 	int		error = 0;
 	int		cnt = 0;
@@ -3905,7 +3908,8 @@ zfs_dirty_inode(struct inode *ip, int flags)
 	/* Preserve the mode, mtime and ctime provided by the inode */
 	ZFS_TIME_ENCODE(&ip->i_atime, atime);
 	ZFS_TIME_ENCODE(&ip->i_mtime, mtime);
-	ZFS_TIME_ENCODE(&ip->i_ctime, ctime);
+	tmp_ctime = zpl_inode_get_ctime(ip);
+	ZFS_TIME_ENCODE(&tmp_ctime, ctime);
 	mode = ip->i_mode;
 
 	zp->z_mode = mode;

module/os/linux/zfs/zfs_znode.c

@@ -542,6 +542,7 @@ zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz,
 	uint64_t links;
 	uint64_t z_uid, z_gid;
 	uint64_t atime[2], mtime[2], ctime[2], btime[2];
+	inode_timespec_t tmp_ctime;
 	uint64_t projid = ZFS_DEFAULT_PROJID;
 	sa_bulk_attr_t bulk[12];
 	int count = 0;
@@ -615,7 +616,8 @@ zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz,
 
 	ZFS_TIME_DECODE(&ip->i_atime, atime);
 	ZFS_TIME_DECODE(&ip->i_mtime, mtime);
-	ZFS_TIME_DECODE(&ip->i_ctime, ctime);
+	ZFS_TIME_DECODE(&tmp_ctime, ctime);
+	zpl_inode_set_ctime_to_ts(ip, tmp_ctime);
 	ZFS_TIME_DECODE(&zp->z_btime, btime);
 
 	ip->i_ino = zp->z_id;
@@ -1195,6 +1197,7 @@ zfs_rezget(znode_t *zp)
 	uint64_t gen;
 	uint64_t z_uid, z_gid;
 	uint64_t atime[2], mtime[2], ctime[2], btime[2];
+	inode_timespec_t tmp_ctime;
 	uint64_t projid = ZFS_DEFAULT_PROJID;
 	znode_hold_t *zh;
 
@@ -1289,7 +1292,8 @@ zfs_rezget(znode_t *zp)
 
 	ZFS_TIME_DECODE(&ZTOI(zp)->i_atime, atime);
 	ZFS_TIME_DECODE(&ZTOI(zp)->i_mtime, mtime);
-	ZFS_TIME_DECODE(&ZTOI(zp)->i_ctime, ctime);
+	ZFS_TIME_DECODE(&tmp_ctime, ctime);
+	zpl_inode_set_ctime_to_ts(ZTOI(zp), tmp_ctime);
 	ZFS_TIME_DECODE(&zp->z_btime, btime);
 
 	if ((uint32_t)gen != ZTOI(zp)->i_generation) {
@@ -1397,7 +1401,7 @@ zfs_zinactive(znode_t *zp)
 boolean_t
 zfs_relatime_need_update(const struct inode *ip)
 {
-	inode_timespec_t now;
+	inode_timespec_t now, tmp_ctime;
 
 	gethrestime(&now);
 	/*
@@ -1408,7 +1412,8 @@ zfs_relatime_need_update(const struct inode *ip)
 	if (zfs_compare_timespec(&ip->i_mtime, &ip->i_atime) >= 0)
 		return (B_TRUE);
 
-	if (zfs_compare_timespec(&ip->i_ctime, &ip->i_atime) >= 0)
+	tmp_ctime = zpl_inode_get_ctime(ip);
+	if (zfs_compare_timespec(&tmp_ctime, &ip->i_atime) >= 0)
 		return (B_TRUE);
 
 	if ((hrtime_t)now.tv_sec - (hrtime_t)ip->i_atime.tv_sec >= 24*60*60)
@@ -1434,7 +1439,7 @@ void
 zfs_tstamp_update_setup(znode_t *zp, uint_t flag, uint64_t mtime[2],
     uint64_t ctime[2])
 {
-	inode_timespec_t now;
+	inode_timespec_t now, tmp_ctime;
 
 	gethrestime(&now);
 
@@ -1451,7 +1456,8 @@ zfs_tstamp_update_setup(znode_t *zp, uint_t flag, uint64_t mtime[2],
 
 	if (flag & ATTR_CTIME) {
 		ZFS_TIME_ENCODE(&now, ctime);
-		ZFS_TIME_DECODE(&(ZTOI(zp)->i_ctime), ctime);
+		ZFS_TIME_DECODE(&tmp_ctime, ctime);
+		zpl_inode_set_ctime_to_ts(ZTOI(zp), tmp_ctime);
 		if (ZTOZSB(zp)->z_use_fuids)
 			zp->z_pflags |= ZFS_ARCHIVE;
 	}

module/os/linux/zfs/zpl_inode.c

@@ -774,7 +774,7 @@ zpl_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
 		return (-EMLINK);
 
 	crhold(cr);
-	ip->i_ctime = current_time(ip);
+	zpl_inode_set_ctime_to_ts(ip, current_time(ip));
 	/* Must have an existing ref, so igrab() cannot return NULL */
 	VERIFY3P(igrab(ip), !=, NULL);
 

module/os/linux/zfs/zpl_xattr.c

@@ -513,7 +513,7 @@ zpl_xattr_set_dir(struct inode *ip, const char *name, const void *value,
 	error = -zfs_write_simple(xzp, value, size, pos, NULL);
 out:
 	if (error == 0) {
-		ip->i_ctime = current_time(ip);
+		zpl_inode_set_ctime_to_ts(ip, current_time(ip));
 		zfs_mark_inode_dirty(ip);
 	}
 
@@ -1011,7 +1011,8 @@ zpl_set_acl_impl(struct inode *ip, struct posix_acl *acl, int type)
 				 */
 				if (ip->i_mode != mode) {
 					ip->i_mode = ITOZ(ip)->z_mode = mode;
-					ip->i_ctime = current_time(ip);
+					zpl_inode_set_ctime_to_ts(ip,
+					    current_time(ip));
 					zfs_mark_inode_dirty(ip);
 				}
 
@@ -1170,7 +1171,7 @@ zpl_init_acl(struct inode *ip, struct inode *dir)
 			return (PTR_ERR(acl));
 		if (!acl) {
 			ITOZ(ip)->z_mode = (ip->i_mode &= ~current_umask());
-			ip->i_ctime = current_time(ip);
+			zpl_inode_set_ctime_to_ts(ip, current_time(ip));
 			zfs_mark_inode_dirty(ip);
 			return (0);
 		}