fs: introduce inode operation ->update_time

Btrfs has to make sure we have space to allocate new blocks in order to modify
the inode, so updating time can fail.  We've gotten around this by having our
own file_update_time but this is kind of a pain, and Christoph has indicated he
would like to make xfs do something different with atime updates.  So introduce
->update_time, where we will deal with i_version an a/m/c time updates and
indicate which changes need to be made.  The normal version just does what it
has always done, updates the time and marks the inode dirty, and then
filesystems can choose to do something different.

I've gone through all of the users of file_update_time and made them check for
errors with the exception of the fault code since it's complicated and I wasn't
quite sure what to do there, also Jan is going to be pushing the file time
updates into page_mkwrite for those who have it so that should satisfy btrfs and
make it not a big deal to check the file_update_time() return code in the
generic fault path. Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index cdc1a9630948..57fc70574d20 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1684,6 +1684,7 @@ struct inode_operations {
         void (*truncate_range)(struct inode *, loff_t, loff_t);
         int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
                       u64 len);
+        int (*update_time)(struct inode *, struct timespec *, int);
 } ____cacheline_aligned;
 
 struct seq_file;
@@ -1843,6 +1844,13 @@ static inline void inode_inc_iversion(struct inode *inode)
        spin_unlock(&inode->i_lock);
 }
 
+enum file_time_flags {
+        S_ATIME = 1,
+        S_MTIME = 2,
+        S_CTIME = 4,
+        S_VERSION = 8,
+};
+
 extern void touch_atime(struct path *);
 static inline void file_accessed(struct file *file)
 {
@@ -2579,7 +2587,7 @@ extern int inode_change_ok(const struct inode *, struct iattr *);
 extern int inode_newsize_ok(const struct inode *, loff_t offset);
 extern void setattr_copy(struct inode *inode, const struct iattr *attr);
 
-extern void file_update_time(struct file *file);
+extern int file_update_time(struct file *file);
 
 extern int generic_show_options(struct seq_file *m, struct dentry *root);
 extern void save_mount_options(struct super_block *sb, char *options);