Ext4 bug fixes for v4.4, including fixes for post-2038 time encodings,

some endian conversion problems with ext4 encryption, potential memory
 leaks after truncate in data=journal mode, and an ocfs2 regression
 caused by a jbd2 performance improvement.
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Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 fixes from Ted Ts'o:
 "Ext4 bug fixes for v4.4, including fixes for post-2038 time encodings,
  some endian conversion problems with ext4 encryption, potential memory
  leaks after truncate in data=journal mode, and an ocfs2 regression
  caused by a jbd2 performance improvement"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  jbd2: fix null committed data return in undo_access
  ext4: add "static" to ext4_seq_##name##_fops struct
  ext4: fix an endianness bug in ext4_encrypted_follow_link()
  ext4: fix an endianness bug in ext4_encrypted_zeroout()
  jbd2: Fix unreclaimed pages after truncate in data=journal mode
  ext4: Fix handling of extended tv_sec

fs/ext4/crypto.c

@@ -389,7 +389,7 @@ int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex)
 	struct ext4_crypto_ctx	*ctx;
 	struct page		*ciphertext_page = NULL;
 	struct bio		*bio;
-	ext4_lblk_t		lblk = ex->ee_block;
+	ext4_lblk_t		lblk = le32_to_cpu(ex->ee_block);
 	ext4_fsblk_t		pblk = ext4_ext_pblock(ex);
 	unsigned int		len = ext4_ext_get_actual_len(ex);
 	int			ret, err = 0;

fs/ext4/ext4.h

@@ -26,6 +26,7 @@
 #include <linux/seqlock.h>
 #include <linux/mutex.h>
 #include <linux/timer.h>
+#include <linux/version.h>
 #include <linux/wait.h>
 #include <linux/blockgroup_lock.h>
 #include <linux/percpu_counter.h>
@@ -727,19 +728,55 @@ struct move_extent {
 	<= (EXT4_GOOD_OLD_INODE_SIZE +			\
 	    (einode)->i_extra_isize))			\
 
+/*
+ * We use an encoding that preserves the times for extra epoch "00":
+ *
+ * extra  msb of                         adjust for signed
+ * epoch  32-bit                         32-bit tv_sec to
+ * bits   time    decoded 64-bit tv_sec  64-bit tv_sec      valid time range
+ * 0 0    1    -0x80000000..-0x00000001  0x000000000 1901-12-13..1969-12-31
+ * 0 0    0    0x000000000..0x07fffffff  0x000000000 1970-01-01..2038-01-19
+ * 0 1    1    0x080000000..0x0ffffffff  0x100000000 2038-01-19..2106-02-07
+ * 0 1    0    0x100000000..0x17fffffff  0x100000000 2106-02-07..2174-02-25
+ * 1 0    1    0x180000000..0x1ffffffff  0x200000000 2174-02-25..2242-03-16
+ * 1 0    0    0x200000000..0x27fffffff  0x200000000 2242-03-16..2310-04-04
+ * 1 1    1    0x280000000..0x2ffffffff  0x300000000 2310-04-04..2378-04-22
+ * 1 1    0    0x300000000..0x37fffffff  0x300000000 2378-04-22..2446-05-10
+ *
+ * Note that previous versions of the kernel on 64-bit systems would
+ * incorrectly use extra epoch bits 1,1 for dates between 1901 and
+ * 1970.  e2fsck will correct this, assuming that it is run on the
+ * affected filesystem before 2242.
+ */
+
 static inline __le32 ext4_encode_extra_time(struct timespec *time)
 {
-       return cpu_to_le32((sizeof(time->tv_sec) > 4 ?
+	u32 extra = sizeof(time->tv_sec) > 4 ?
-			   (time->tv_sec >> 32) & EXT4_EPOCH_MASK : 0) |
+		((time->tv_sec - (s32)time->tv_sec) >> 32) & EXT4_EPOCH_MASK : 0;
-                          ((time->tv_nsec << EXT4_EPOCH_BITS) & EXT4_NSEC_MASK));
+	return cpu_to_le32(extra | (time->tv_nsec << EXT4_EPOCH_BITS));
 }
 
 static inline void ext4_decode_extra_time(struct timespec *time, __le32 extra)
 {
-       if (sizeof(time->tv_sec) > 4)
+	if (unlikely(sizeof(time->tv_sec) > 4 &&
-	       time->tv_sec |= (__u64)(le32_to_cpu(extra) & EXT4_EPOCH_MASK)
+			(extra & cpu_to_le32(EXT4_EPOCH_MASK)))) {
-			       << 32;
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4,20,0)
-       time->tv_nsec = (le32_to_cpu(extra) & EXT4_NSEC_MASK) >> EXT4_EPOCH_BITS;
+		/* Handle legacy encoding of pre-1970 dates with epoch
+		 * bits 1,1.  We assume that by kernel version 4.20,
+		 * everyone will have run fsck over the affected
+		 * filesystems to correct the problem.  (This
+		 * backwards compatibility may be removed before this
+		 * time, at the discretion of the ext4 developers.)
+		 */
+		u64 extra_bits = le32_to_cpu(extra) & EXT4_EPOCH_MASK;
+		if (extra_bits == 3 && ((time->tv_sec) & 0x80000000) != 0)
+			extra_bits = 0;
+		time->tv_sec += extra_bits << 32;
+#else
+		time->tv_sec += (u64)(le32_to_cpu(extra) & EXT4_EPOCH_MASK) << 32;
+#endif
+	}
+	time->tv_nsec = (le32_to_cpu(extra) & EXT4_NSEC_MASK) >> EXT4_EPOCH_BITS;
 }
 
 #define EXT4_INODE_SET_XTIME(xtime, inode, raw_inode)			       \

fs/ext4/symlink.c

@@ -52,7 +52,7 @@ static const char *ext4_encrypted_follow_link(struct dentry *dentry, void **cook
 	/* Symlink is encrypted */
 	sd = (struct ext4_encrypted_symlink_data *)caddr;
 	cstr.name = sd->encrypted_path;
-	cstr.len  = le32_to_cpu(sd->len);
+	cstr.len  = le16_to_cpu(sd->len);
 	if ((cstr.len +
 	     sizeof(struct ext4_encrypted_symlink_data) - 1) >
 	    max_size) {

fs/ext4/sysfs.c

@@ -358,7 +358,7 @@ static int name##_open(struct inode *inode, struct file *file) \
 	return single_open(file, ext4_seq_##name##_show, PDE_DATA(inode)); \
 } \
 \
-const struct file_operations ext4_seq_##name##_fops = { \
+static const struct file_operations ext4_seq_##name##_fops = { \
 	.owner		= THIS_MODULE, \
 	.open		= name##_open, \
 	.read		= seq_read, \

fs/jbd2/transaction.c

@@ -1009,7 +1009,8 @@ out:
 }
 
 /* Fast check whether buffer is already attached to the required transaction */
-static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh)
+static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh,
+							bool undo)
 {
 	struct journal_head *jh;
 	bool ret = false;
@@ -1036,6 +1037,9 @@ static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh)
 	jh = READ_ONCE(bh->b_private);
 	if (!jh)
 		goto out;
+	/* For undo access buffer must have data copied */
+	if (undo && !jh->b_committed_data)
+		goto out;
 	if (jh->b_transaction != handle->h_transaction &&
 	    jh->b_next_transaction != handle->h_transaction)
 		goto out;
@@ -1073,7 +1077,7 @@ int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
 	struct journal_head *jh;
 	int rc;
 
-	if (jbd2_write_access_granted(handle, bh))
+	if (jbd2_write_access_granted(handle, bh, false))
 		return 0;
 
 	jh = jbd2_journal_add_journal_head(bh);
@@ -1210,7 +1214,7 @@ int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
 	char *committed_data = NULL;
 
 	JBUFFER_TRACE(jh, "entry");
-	if (jbd2_write_access_granted(handle, bh))
+	if (jbd2_write_access_granted(handle, bh, true))
 		return 0;
 
 	jh = jbd2_journal_add_journal_head(bh);
@@ -2152,6 +2156,7 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
 
 		if (!buffer_dirty(bh)) {
 			/* bdflush has written it.  We can drop it now */
+			__jbd2_journal_remove_checkpoint(jh);
 			goto zap_buffer;
 		}
 
@@ -2181,6 +2186,7 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
 				/* The orphan record's transaction has
 				 * committed.  We can cleanse this buffer */
 				clear_buffer_jbddirty(bh);
+				__jbd2_journal_remove_checkpoint(jh);
 				goto zap_buffer;
 			}
 		}