ext4: Add nanosecond timestamps

This patch adds nanosecond timestamps for ext4. This involves adding
*time_extra fields to the ext4_inode to extend the timestamps to
64-bits.  Creation time is also added by this patch.

These extended fields will fit into an inode if the filesystem was
formatted with large inodes (-I 256 or larger) and there are currently
no EAs consuming all of the available space. For new inodes we always
reserve enough space for the kernel's known extended fields, but for
inodes created with an old kernel this might not have been the case. So
this patch also adds the EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE feature
flag(ro-compat so that older kernels can't create inodes with a smaller
extra_isize). which indicates if the fields fitting inside
s_min_extra_isize are available or not.  If the expansion of inodes if
unsuccessful then this feature will be disabled.  This feature is only
enabled if requested by the sysadmin.

None of the extended inode fields is critical for correct filesystem
operation.

Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
Signed-off-by: Kalpak Shah <kalpak@clusterfs.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 28 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index af0835187e76..b47259f6f39c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1651,6 +1651,8 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
                                 sbi->s_inode_size);
                         goto failed_mount;
                 }
+                if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE)
+                        sb->s_time_gran = 1 << (EXT4_EPOCH_BITS - 2);
         }
         sbi->s_frag_size = EXT4_MIN_FRAG_SIZE <<
                                    le32_to_cpu(es->s_log_frag_size);
@@ -1874,6 +1876,32 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
         }
 
         ext4_setup_super (sb, es, sb->s_flags & MS_RDONLY);
+
+        /* determine the minimum size of new large inodes, if present */
+        if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE) {
+                sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
+                                                     EXT4_GOOD_OLD_INODE_SIZE;
+                if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+                                       EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE)) {
+                        if (sbi->s_want_extra_isize <
+                            le16_to_cpu(es->s_want_extra_isize))
+                                sbi->s_want_extra_isize =
+                                        le16_to_cpu(es->s_want_extra_isize);
+                        if (sbi->s_want_extra_isize <
+                            le16_to_cpu(es->s_min_extra_isize))
+                                sbi->s_want_extra_isize =
+                                        le16_to_cpu(es->s_min_extra_isize);
+                }
+        }
+        /* Check if enough inode space is available */
+        if (EXT4_GOOD_OLD_INODE_SIZE + sbi->s_want_extra_isize >
+                                                        sbi->s_inode_size) {
+                sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
+                                                       EXT4_GOOD_OLD_INODE_SIZE;
+                printk(KERN_INFO "EXT4-fs: required extra inode space not"
+                        "available.\n");
+        }
+
         /*
          * akpm: core read_super() calls in here with the superblock locked.
          * That deadlocks, because orphan cleanup needs to lock the superblock