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Subject[PATCH 3/4] unionfs: restructure unionfs_setattr
In order to fix unionfs truncation, we need to move the lower notify_change
out of the loop in unionfs_setattr. But when I came to do that, I couldn't
understand that loop at all: its continues and breaks and gotos are obscure,
most particularly the "if (copyup || (bindex != bstart)) continue;" which
seems to make a nonsense of the whole thing.
Here's my attempt to restructure it, prior to making the functional change
in the next patch; but I may have misunderstood badly, please check - I've
not tested it beyond my degenerate dirs=/tmpfs case, which hardly tests it.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
---
fs/unionfs/inode.c | 64 ++++++++++++++++++-------------------------
1 file changed, 28 insertions(+), 36 deletions(-)
--- 2.6.24-rc5-mm1/fs/unionfs/inode.c 2007-12-05 10:38:38.000000000 +0000
+++ unionfs3/fs/unionfs/inode.c 2007-12-05 18:50:52.000000000 +0000
@@ -1004,11 +1004,10 @@ static int unionfs_setattr(struct dentry
{
int err = 0;
struct dentry *lower_dentry;
- struct inode *inode = NULL;
- struct inode *lower_inode = NULL;
+ struct inode *inode;
+ struct inode *lower_inode;
int bstart, bend, bindex;
- int i;
- int copyup = 0;
+ loff_t size;

unionfs_read_lock(dentry->d_sb);
unionfs_lock_dentry(dentry);
@@ -1029,50 +1028,43 @@ static int unionfs_setattr(struct dentry
if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
ia->ia_valid &= ~ATTR_MODE;

- for (bindex = bstart; (bindex <= bend) || (bindex == bstart);
- bindex++) {
- lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
- if (!lower_dentry)
- continue;
- BUG_ON(lower_dentry->d_inode == NULL);
-
+ lower_dentry = unionfs_lower_dentry(dentry);
+ if (lower_dentry) {
/* If the file is on a read only branch */
- if (is_robranch_super(dentry->d_sb, bindex)
+ if (is_robranch_super(dentry->d_sb, bstart)
|| IS_RDONLY(lower_dentry->d_inode)) {
- if (copyup || (bindex != bstart))
- continue;
- /* Only if its the leftmost file, copyup the file */
- for (i = bstart - 1; i >= 0; i--) {
- loff_t size = i_size_read(dentry->d_inode);
- if (ia->ia_valid & ATTR_SIZE)
- size = ia->ia_size;
+
+ if (ia->ia_valid & ATTR_SIZE)
+ size = ia->ia_size;
+ else
+ size = i_size_read(inode);
+
+ for (bindex = bstart - 1; bindex >= 0; bindex--) {
err = copyup_dentry(dentry->d_parent->d_inode,
- dentry, bstart, i,
+ dentry, bstart, bindex,
dentry->d_name.name,
dentry->d_name.len,
NULL, size);
-
- if (!err) {
- copyup = 1;
- lower_dentry =
- unionfs_lower_dentry(dentry);
+ if (!err)
break;
- }
- /*
- * if error is in the leftmost branch, pass
- * it up.
- */
- if (i == 0)
- goto out;
}

+ if (err)
+ goto out;
+ lower_dentry = unionfs_lower_dentry(dentry);
+ }
+ } else {
+ for (bindex = bstart + 1; bindex <= bend; bindex++) {
+ lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ if (lower_dentry)
+ break;
}
- err = notify_change(lower_dentry, ia);
- if (err)
- goto out;
- break;
}

+ err = notify_change(lower_dentry, ia);
+ if (err)
+ goto out;
+
/* for mmap */
if (ia->ia_valid & ATTR_SIZE) {
if (ia->ia_size != i_size_read(inode)) {

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