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[PATCH v3 2/5] fs: Add inode_update_time_writable

To: linux-kernel@xxxxxxxxxxxxxxx
Subject: [PATCH v3 2/5] fs: Add inode_update_time_writable
From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Date: Fri, 16 Aug 2013 16:22:09 -0700
Cc: linux-ext4@xxxxxxxxxxxxxxx, Dave Chinner <david@xxxxxxxxxxxxx>, Theodore Ts'o <tytso@xxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, xfs@xxxxxxxxxxx, Jan Kara <jack@xxxxxxx>, Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>, Christoph Hellwig <hch@xxxxxxxxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <cover.1376679411.git.luto@xxxxxxxxxxxxxx>
In-reply-to: <cover.1376679411.git.luto@xxxxxxxxxxxxxx>
References: <cover.1376679411.git.luto@xxxxxxxxxxxxxx>
References: <cover.1376679411.git.luto@xxxxxxxxxxxxxx>
This is like file_update_time, except that it acts on a struct inode *
instead of a struct file *.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
---
 fs/inode.c         | 72 ++++++++++++++++++++++++++++++++++++++++++------------
 include/linux/fs.h |  1 +
 2 files changed, 58 insertions(+), 15 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index d6dfb09..bc90c12 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1637,6 +1637,34 @@ int file_remove_suid(struct file *file)
 }
 EXPORT_SYMBOL(file_remove_suid);
 
+/*
+ * This does the work that's common to file_update_time and
+ * inode_update_time.
+ */
+static int prepare_update_cmtime(struct inode *inode, struct timespec *now)
+{
+       int sync_it;
+
+       /* First try to exhaust all avenues to not sync */
+       if (IS_NOCMTIME(inode))
+               return 0;
+
+       *now = current_fs_time(inode->i_sb);
+       if (!timespec_equal(&inode->i_mtime, now))
+               sync_it = S_MTIME;
+
+       if (!timespec_equal(&inode->i_ctime, now))
+               sync_it |= S_CTIME;
+
+       if (IS_I_VERSION(inode))
+               sync_it |= S_VERSION;
+
+       if (!sync_it)
+               return 0;
+
+       return sync_it;
+}
+
 /**
  *     file_update_time        -       update mtime and ctime time
  *     @file: file accessed
@@ -1654,23 +1682,9 @@ int file_update_time(struct file *file)
 {
        struct inode *inode = file_inode(file);
        struct timespec now;
-       int sync_it = 0;
+       int sync_it = prepare_update_cmtime(inode, &now);
        int ret;
 
-       /* First try to exhaust all avenues to not sync */
-       if (IS_NOCMTIME(inode))
-               return 0;
-
-       now = current_fs_time(inode->i_sb);
-       if (!timespec_equal(&inode->i_mtime, &now))
-               sync_it = S_MTIME;
-
-       if (!timespec_equal(&inode->i_ctime, &now))
-               sync_it |= S_CTIME;
-
-       if (IS_I_VERSION(inode))
-               sync_it |= S_VERSION;
-
        if (!sync_it)
                return 0;
 
@@ -1685,6 +1699,34 @@ int file_update_time(struct file *file)
 }
 EXPORT_SYMBOL(file_update_time);
 
+/**
+ *     inode_update_time_writable      -       update mtime and ctime time
+ *     @inode: inode accessed
+ *
+ *     This is like file_update_time, but it assumes the mnt is writable
+ *     and takes an inode parameter instead.  (We need to assume the mnt
+ *     was writable because inodes aren't associated with any particular
+ *     mnt.
+ */
+
+int inode_update_time_writable(struct inode *inode)
+{
+       struct timespec now;
+       int sync_it = prepare_update_cmtime(inode, &now);
+       int ret;
+
+       if (!sync_it)
+               return 0;
+
+       /* sb_start_pagefault and update_time can both sleep. */
+       sb_start_pagefault(inode->i_sb);
+       ret = update_time(inode, &now, sync_it);
+       sb_end_pagefault(inode->i_sb);
+
+       return ret;
+}
+EXPORT_SYMBOL(inode_update_time_writable);
+
 int inode_needs_sync(struct inode *inode)
 {
        if (IS_SYNC(inode))
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9818747..86cf0a4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2590,6 +2590,7 @@ extern int inode_newsize_ok(const struct inode *, loff_t 
offset);
 extern void setattr_copy(struct inode *inode, const struct iattr *attr);
 
 extern int file_update_time(struct file *file);
+extern int inode_update_time_writable(struct inode *inode);
 
 extern int generic_show_options(struct seq_file *m, struct dentry *root);
 extern void save_mount_options(struct super_block *sb, char *options);
-- 
1.8.3.1

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