There are couple of places where we need to know if file is already copied
up (in lockless manner). Right now its open coded and there are only
two conditions to check. Soon this patch series will introduce another
condition to check and Amir wants to introduce one more. So introduce
a helper instead to check this so that code is easier to read.
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/copy_up.c | 19 ++-----------------
fs/overlayfs/overlayfs.h | 1 +
fs/overlayfs/util.c | 24 +++++++++++++++++++++++-
3 files changed, 26 insertions(+), 18 deletions(-)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 82d66e96be0f..b6fa5830c4c6 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -234,8 +234,7 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
{
- if (ovl_dentry_upper(dentry) &&
- ovl_dentry_has_upper_alias(dentry))
+ if (ovl_already_copied_up(dentry))
return false;
if (special_file(d_inode(dentry)->i_mode))
@@ -701,21 +700,7 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags)
struct dentry *next;
struct dentry *parent;
- /*
- * Check if copy-up has happened as well as for upper alias (in
- * case of hard links) is there.
- *
- * Both checks are lockless:
- * - false negatives: will recheck under oi->lock
- * - false positives:
- * + ovl_dentry_upper() uses memory barriers to ensure the
- * upper dentry is up-to-date
- * + ovl_dentry_has_upper_alias() relies on locking of
- * upper parent i_rwsem to prevent reordering copy-up
- * with rename.
- */
- if (ovl_dentry_upper(dentry) &&
- ovl_dentry_has_upper_alias(dentry))
+ if (ovl_already_copied_up(dentry))
break;
next = dget(dentry);
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 13eab09a6b6f..7f9a79b5a2b5 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -227,6 +227,7 @@ bool ovl_is_whiteout(struct dentry *dentry);
struct file *ovl_path_open(struct path *path, int flags);
int ovl_copy_up_start(struct dentry *dentry);
void ovl_copy_up_end(struct dentry *dentry);
+bool ovl_already_copied_up(struct dentry *dentry);
bool ovl_check_origin_xattr(struct dentry *dentry);
bool ovl_check_dir_xattr(struct dentry *dentry, const char *name);
int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 77dc00438d54..572bf46e9f2e 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -314,13 +314,35 @@ struct file *ovl_path_open(struct path *path, int flags)
return dentry_open(path, flags | O_NOATIME, current_cred());
}
+bool ovl_already_copied_up(struct dentry *dentry)
+{
+ /*
+ * Check if copy-up has happened as well as for upper alias (in
+ * case of hard links) is there.
+ *
+ * Both checks are lockless:
+ * - false negatives: will recheck under oi->lock
+ * - false positives:
+ * + ovl_dentry_upper() uses memory barriers to ensure the
+ * upper dentry is up-to-date
+ * + ovl_dentry_has_upper_alias() relies on locking of
+ * upper parent i_rwsem to prevent reordering copy-up
+ * with rename.
+ */
+ if (ovl_dentry_upper(dentry) &&
+ ovl_dentry_has_upper_alias(dentry))
+ return true;
+
+ return false;
+}
+
int ovl_copy_up_start(struct dentry *dentry)
{
struct ovl_inode *oi = OVL_I(d_inode(dentry));
int err;
err = mutex_lock_interruptible(&oi->lock);
- if (!err && ovl_dentry_has_upper_alias(dentry)) {
+ if (!err && ovl_already_copied_up(dentry)) {
err = 1; /* Already copied up */
mutex_unlock(&oi->lock);
}
--
2.13.6
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