5 files changed, 81 insertions, 2 deletions

diff --git a/fs/ubifs/Kconfig b/fs/ubifs/Kconfig
index ba66d508006a..7ff7712f284e 100644
--- a/fs/ubifs/Kconfig
+++ b/fs/ubifs/Kconfig
@@ -35,3 +35,18 @@ config UBIFS_FS_ZLIB
         default y
         help
           Zlib compresses better than LZO but it is slower. Say 'Y' if unsure.
+
+config UBIFS_ATIME_SUPPORT
+        bool "Access time support" if UBIFS_FS
+        depends on UBIFS_FS
+        default n
+        help
+          Originally UBIFS did not support atime, because it looked like a bad idea due
+          increased flash wear. This option adds atime support and it is disabled by default
+          to preserve the old behavior. If you enable this option, UBIFS starts updating atime,
+          which means that file-system read operations will cause writes (inode atime
+          updates). This may affect file-system performance and increase flash device wear,
+          so be careful. How often atime is updated depends on the selected strategy:
+          strictatime is the "heavy", relatime is "lighter", etc.
+
+          If unsure, say 'N'
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index a2f9d978b110..e49bd2808bf3 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -1186,6 +1186,9 @@ const struct inode_operations ubifs_dir_inode_operations = {
         .getxattr    = ubifs_getxattr,
         .listxattr   = ubifs_listxattr,
         .removexattr = ubifs_removexattr,
+#ifdef CONFIG_UBIFS_ATIME_SUPPORT
+        .update_time = ubifs_update_time,
+#endif
 };
 
 const struct file_operations ubifs_dir_operations = {
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index a3dfe2ae79f2..0edc12856147 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -1354,6 +1354,47 @@ static inline int mctime_update_needed(const struct inode *inode,
         return 0;
 }
 
+#ifdef CONFIG_UBIFS_ATIME_SUPPORT
+/**
+ * ubifs_update_time - update time of inode.
+ * @inode: inode to update
+ *
+ * This function updates time of the inode.
+ */
+int ubifs_update_time(struct inode *inode, struct timespec *time,
+                             int flags)
+{
+        struct ubifs_inode *ui = ubifs_inode(inode);
+        struct ubifs_info *c = inode->i_sb->s_fs_info;
+        struct ubifs_budget_req req = { .dirtied_ino = 1,
+                        .dirtied_ino_d = ALIGN(ui->data_len, 8) };
+        int iflags = I_DIRTY_TIME;
+        int err, release;
+
+        err = ubifs_budget_space(c, &req);
+        if (err)
+                return err;
+
+        mutex_lock(&ui->ui_mutex);
+        if (flags & S_ATIME)
+                inode->i_atime = *time;
+        if (flags & S_CTIME)
+                inode->i_ctime = *time;
+        if (flags & S_MTIME)
+                inode->i_mtime = *time;
+
+        if (!(inode->i_sb->s_flags & MS_LAZYTIME))
+                iflags |= I_DIRTY_SYNC;
+
+        release = ui->dirty;
+        __mark_inode_dirty(inode, iflags);
+        mutex_unlock(&ui->ui_mutex);
+        if (release)
+                ubifs_release_budget(c, &req);
+        return 0;
+}
+#endif
+
 /**
  * update_ctime - update mtime and ctime of an inode.
  * @inode: inode to update
@@ -1537,6 +1578,9 @@ static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma)
         if (err)
                 return err;
         vma->vm_ops = &ubifs_file_vm_ops;
+#ifdef CONFIG_UBIFS_ATIME_SUPPORT
+        file_accessed(file);
+#endif
         return 0;
 }
 
@@ -1557,6 +1601,9 @@ const struct inode_operations ubifs_file_inode_operations = {
         .getxattr    = ubifs_getxattr,
         .listxattr   = ubifs_listxattr,
         .removexattr = ubifs_removexattr,
+#ifdef CONFIG_UBIFS_ATIME_SUPPORT
+        .update_time = ubifs_update_time,
+#endif
 };
 
 const struct inode_operations ubifs_symlink_inode_operations = {
@@ -1568,6 +1615,9 @@ const struct inode_operations ubifs_symlink_inode_operations = {
         .getxattr    = ubifs_getxattr,
         .listxattr   = ubifs_listxattr,
         .removexattr = ubifs_removexattr,
+#ifdef CONFIG_UBIFS_ATIME_SUPPORT
+        .update_time = ubifs_update_time,
+#endif
 };
 
 const struct file_operations ubifs_file_operations = {
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 9547a27868ad..8ee3133dd8e4 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -128,7 +128,10 @@ struct inode *ubifs_iget(struct super_block *sb, unsigned long inum)
         if (err)
                 goto out_ino;
 
-        inode->i_flags |= (S_NOCMTIME | S_NOATIME);
+        inode->i_flags |= S_NOCMTIME;
+#ifndef CONFIG_UBIFS_ATIME_SUPPORT
+        inode->i_flags |= S_NOATIME;
+#endif
         set_nlink(inode, le32_to_cpu(ino->nlink));
         i_uid_write(inode, le32_to_cpu(ino->uid));
         i_gid_write(inode, le32_to_cpu(ino->gid));
@@ -2139,7 +2142,12 @@ static struct dentry *ubifs_mount(struct file_system_type *fs_type, int flags,
                 if (err)
                         goto out_deact;
                 /* We do not support atime */
-                sb->s_flags |= MS_ACTIVE | MS_NOATIME;
+                sb->s_flags |= MS_ACTIVE;
+#ifndef CONFIG_UBIFS_ATIME_SUPPORT
+                sb->s_flags |= MS_NOATIME;
+#else
+                ubifs_msg(c, "full atime support is enabled.");
+#endif
         }
 
         /* 'fill_super()' opens ubi again so we must close it here */
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 6ef2415aad9d..01142e129d16 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1746,6 +1746,9 @@ int ubifs_calc_dark(const struct ubifs_info *c, int spc);
 /* file.c */
 int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync);
 int ubifs_setattr(struct dentry *dentry, struct iattr *attr);
+#ifdef CONFIG_UBIFS_ATIME_SUPPORT
+int ubifs_update_time(struct inode *inode, struct timespec *time, int flags);
+#endif
 
 /* dir.c */
 struct inode *ubifs_new_inode(struct ubifs_info *c, const struct inode *dir,