From: Erez Zadok <[EMAIL PROTECTED]>
Utility functions to check if lower dentries/inodes are newer than upper
ones, and purging cached data if lower objects are newer. Also passed flag
to our d_revalidate_chain, to tell it if the caller may be writing data or
just reading it.
[jsipek: changed purge_inode_data to take a struct inode]
Signed-off-by: Erez Zadok <[EMAIL PROTECTED]>
Signed-off-by: Josef 'Jeff' Sipek <[EMAIL PROTECTED]>
---
fs/unionfs/commonfops.c |2 +-
fs/unionfs/dentry.c | 127 --
fs/unionfs/inode.c | 24 ++---
fs/unionfs/rename.c |4 +-
fs/unionfs/super.c |2 +-
fs/unionfs/union.h |3 +-
fs/unionfs/unlink.c | 12 +++-
fs/unionfs/xattr.c |8 ++--
8 files changed, 155 insertions(+), 27 deletions(-)
diff --git a/fs/unionfs/commonfops.c b/fs/unionfs/commonfops.c
index 28cb4e9..0dc7492 100644
--- a/fs/unionfs/commonfops.c
+++ b/fs/unionfs/commonfops.c
@@ -287,7 +287,7 @@ int unionfs_file_revalidate(struct file *file, int
willwrite)
* but not unhashed dentries.
*/
if (!d_deleted(dentry) &&
- !__unionfs_d_revalidate_chain(dentry, NULL)) {
+ !__unionfs_d_revalidate_chain(dentry, NULL, willwrite)) {
err = -ESTALE;
goto out_nofree;
}
diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index 4a3c479..c7bbeca 100644
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -35,7 +35,6 @@ static int __unionfs_d_revalidate_one(struct dentry *dentry,
int positive = 0;
int locked = 0;
int interpose_flag;
-
struct nameidata lowernd; /* TODO: be gentler to the stack */
if (nd)
@@ -158,7 +157,7 @@ static int __unionfs_d_revalidate_one(struct dentry *dentry,
|| !lower_dentry->d_op->d_revalidate)
continue;
if (!lower_dentry->d_op->d_revalidate(lower_dentry,
- &lowernd))
+ &lowernd))
valid = 0;
}
@@ -184,10 +183,92 @@ out:
}
/*
+ * Determine if the lower inode objects have changed from below the unionfs
+ * inode. Return 1 if changed, 0 otherwise.
+ */
+int is_newer_lower(const struct dentry *dentry)
+{
+ int bindex;
+ struct inode *inode;
+ struct inode *lower_inode;
+
+ /* ignore if we're called on semi-initialized dentries/inodes */
+ if (!dentry || !UNIONFS_D(dentry))
+ return 0;
+ inode = dentry->d_inode;
+ if (!inode || !UNIONFS_I(inode) ||
+ ibstart(inode) < 0 || ibend(inode) < 0)
+ return 0;
+
+ for (bindex = ibstart(inode); bindex <= ibend(inode); bindex++) {
+ lower_inode = unionfs_lower_inode_idx(inode, bindex);
+ if (!lower_inode)
+ continue;
+ /*
+* We may want to apply other tests to determine if the
+* lower inode's data has changed, but checking for changed
+* ctime and mtime on the lower inode should be enough.
+*/
+ if (timespec_compare(&inode->i_mtime,
+&lower_inode->i_mtime) < 0) {
+ printk("unionfs: new lower inode mtime "
+ "(bindex=%d, name=%s)\n", bindex,
+ dentry->d_name.name);
+ return 1; /* mtime changed! */
+ }
+ if (timespec_compare(&inode->i_ctime,
+&lower_inode->i_ctime) < 0) {
+ printk("unionfs: new lower inode ctime "
+ "(bindex=%d, name=%s)\n", bindex,
+ dentry->d_name.name);
+ return 1; /* ctime changed! */
+ }
+ }
+ return 0; /* default: lower is not newer */
+}
+
+/*
+ * Purge/remove/unmap all date pages of a unionfs inode. This is called
+ * when the lower inode has changed, and we have to force processes to get
+ * the new data.
+ *
+ * XXX: Our implementation works in that as long as a user process will have
+ * caused Unionfs to be called, directly or indirectly, even to just do
+ * ->d_revalidate; then we will have purged the current Unionfs data and the
+ * process will see the new data. For example, a process that continually
+ * re-reads the same file's data will see the NEW data as soon as the lower
+ * file had changed, upon the next read(2) syscall (even if the file is
+ * still open!) However, this doesn't work when the process re-reads the
+ * open file's data via mmap(2) (unless the user unmaps/closes the file and
+ * remaps/reopens it). Once we respond to ->readpage(s), then the kernel
+ * maps the page into the process's address space and there doesn't appear
+
