commit d3be903466e816eab59fc0b006e16cc6d166dc92
Author: Erez_Zadok <[EMAIL PROTECTED]>
Date: Fri Nov 16 13:47:27 2007 -0500
Unionfs: introduce two functions to maintain time invariants
A new function unionfs_copy_attr_times to maintain the inode time invariants
as per the Unionfs design (i.e., lower times should never be newer than our
times), as documented in Documentation/filesystems/unionfs/concepts.txt.
The second function, unionfs_copy_attr_all, is the unionfs-specific function
to copy all attributes: it uses the special Unionfs handling of hard-links
(via unionfs_get_nlinks) and it uses the special a/c/mtime handling (via
unionfs_copy_attr_times). This second function is the special
fanout-version of fsstack_copy_attr_all, which was simplified for
linear-stack stackable file systems.
Signed-off-by: Erez Zadok <[EMAIL PROTECTED]>
diff --git a/fs/unionfs/fanout.h b/fs/unionfs/fanout.h
index 1f4e4cb..e40d7fb 100644
--- a/fs/unionfs/fanout.h
+++ b/fs/unionfs/fanout.h
@@ -256,4 +256,52 @@ static inline void verify_locked(struct dentry *d)
BUG_ON(!mutex_is_locked(&UNIONFS_D(d)->lock));
}
+/* copy a/m/ctime from the lower branch with the newest times */
+static inline void unionfs_copy_attr_times(struct inode *upper)
+{
+ int bindex;
+ struct inode *lower;
+
+ if (!upper)
+ return;
+ for (bindex=ibstart(upper); bindex <= ibend(upper); bindex++) {
+ lower = unionfs_lower_inode_idx(upper, bindex);
+ if (!lower)
+ continue; /* not all lower dir objects may exist */
+ if (timespec_compare(&upper->i_mtime, &lower->i_mtime) < 0)
+ upper->i_mtime = lower->i_mtime;
+ if (timespec_compare(&upper->i_ctime, &lower->i_ctime) < 0)
+ upper->i_ctime = lower->i_ctime;
+ if (timespec_compare(&upper->i_atime, &lower->i_atime) < 0)
+ upper->i_atime = lower->i_atime;
+ /* XXX: should we notify_change on our upper inode? */
+ }
+}
+
+/*
+ * A unionfs/fanout version of fsstack_copy_attr_all. Uses a
+ * unionfs_get_nlinks to properly calcluate the number of links to a file.
+ * Also, copies the max() of all a/m/ctimes for all lower inodes (which is
+ * important if the lower inode is a directory type)
+ */
+static inline void unionfs_copy_attr_all(struct inode *dest,
+ const struct inode *src)
+{
+ dest->i_mode = src->i_mode;
+ dest->i_uid = src->i_uid;
+ dest->i_gid = src->i_gid;
+ dest->i_rdev = src->i_rdev;
+
+ unionfs_copy_attr_times(dest);
+
+ dest->i_blkbits = src->i_blkbits;
+ dest->i_flags = src->i_flags;
+
+ /*
+ * Update the nlinks AFTER updating the above fields, because the
+ * get_links callback may depend on them.
+ */
+ dest->i_nlink = unionfs_get_nlinks(dest);
+}
+
#endif /* not _FANOUT_H */
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