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Subject[PATCH 22/28] ovl: Set redirect on metacopy files upon rename
Date
From: Vivek Goyal <vgoyal@redhat.com>

Set redirect on metacopy files upon rename. This will help find data
dentry in lower dirs.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/overlayfs/dir.c | 66 +++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 46 insertions(+), 20 deletions(-)

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 8d8e063e4706..1658961a9762 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -873,13 +873,13 @@ static bool ovl_can_move(struct dentry *dentry)
!d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry);
}

-static char *ovl_get_redirect(struct dentry *dentry, bool samedir)
+static char *ovl_get_redirect(struct dentry *dentry, bool abs_redirect)
{
char *buf, *ret;
struct dentry *d, *tmp;
int buflen = ovl_redirect_max + 1;

- if (samedir) {
+ if (!abs_redirect) {
ret = kstrndup(dentry->d_name.name, dentry->d_name.len,
GFP_KERNEL);
goto out;
@@ -933,15 +933,43 @@ static char *ovl_get_redirect(struct dentry *dentry, bool samedir)
return ret ? ret : ERR_PTR(-ENOMEM);
}

+static bool ovl_need_absolute_redirect(struct dentry *dentry, bool samedir)
+{
+ struct dentry *lowerdentry;
+
+ if (!samedir)
+ return true;
+
+ if (d_is_dir(dentry))
+ return false;
+
+ /*
+ * For non-dir hardlinked files, we need absolute redirects
+ * in general as two upper hardlinks could be in different
+ * dirs. We could put a relative redirect now and convert
+ * it to absolute redirect later. But when nlink > 1 and
+ * indexing is on, that means relative redirect needs to be
+ * converted to absolute during copy up of another lower
+ * hardllink as well.
+ *
+ * So without optimizing too much, just check if lower is
+ * a hard link or not. If lower is hard link, put absolute
+ * redirect.
+ */
+ lowerdentry = ovl_dentry_lower(dentry);
+ return (d_inode(lowerdentry)->i_nlink > 1);
+}
+
static int ovl_set_redirect(struct dentry *dentry, bool samedir)
{
int err;
const char *redirect = ovl_dentry_get_redirect(dentry);
+ bool absolute_redirect = ovl_need_absolute_redirect(dentry, samedir);

- if (redirect && (samedir || redirect[0] == '/'))
+ if (redirect && (!absolute_redirect || redirect[0] == '/'))
return 0;

- redirect = ovl_get_redirect(dentry, samedir);
+ redirect = ovl_get_redirect(dentry, absolute_redirect);
if (IS_ERR(redirect))
return PTR_ERR(redirect);

@@ -1117,22 +1145,20 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
goto out_dput;

err = 0;
- if (is_dir) {
- if (ovl_type_merge_or_lower(old))
- err = ovl_set_redirect(old, samedir);
- else if (!old_opaque && ovl_type_merge(new->d_parent))
- err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
- if (err)
- goto out_dput;
- }
- if (!overwrite && new_is_dir) {
- if (ovl_type_merge_or_lower(new))
- err = ovl_set_redirect(new, samedir);
- else if (!new_opaque && ovl_type_merge(old->d_parent))
- err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
- if (err)
- goto out_dput;
- }
+ if (ovl_type_merge_or_lower(old))
+ err = ovl_set_redirect(old, samedir);
+ else if (is_dir && !old_opaque && ovl_type_merge(new->d_parent))
+ err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
+ if (err)
+ goto out_dput;
+
+ if (!overwrite && ovl_type_merge_or_lower(new))
+ err = ovl_set_redirect(new, samedir);
+ else if (!overwrite && new_is_dir && !new_opaque &&
+ ovl_type_merge(old->d_parent))
+ err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
+ if (err)
+ goto out_dput;

err = ovl_do_rename(old_upperdir->d_inode, olddentry,
new_upperdir->d_inode, newdentry, flags);
--
2.14.3
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