diff options
| -rw-r--r-- | fs/overlayfs/copy_up.c | 20 | ||||
| -rw-r--r-- | fs/overlayfs/overlayfs.h | 1 | ||||
| -rw-r--r-- | fs/overlayfs/util.c | 26 |
3 files changed, 28 insertions, 19 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index d23467976725..aa3c62a4e462 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -761,21 +761,7 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags) struct dentry *next; struct dentry *parent = NULL; - /* - * 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) || disconnected)) + if (ovl_already_copied_up(dentry)) break; next = dget(dentry); @@ -803,9 +789,7 @@ int ovl_copy_up_flags(struct dentry *dentry, int flags) static bool ovl_open_need_copy_up(struct dentry *dentry, int flags) { /* Copy up of disconnected dentry does not set upper alias */ - if (ovl_dentry_upper(dentry) && - (ovl_dentry_has_upper_alias(dentry) || - (dentry->d_flags & DCACHE_DISCONNECTED))) + if (ovl_already_copied_up(dentry)) return false; if (special_file(d_inode(dentry)->i_mode)) diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index c0318b5a50f0..206e588df095 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -238,6 +238,7 @@ 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 25d202b47326..43235294e77b 100644 --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -377,13 +377,37 @@ 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) +{ + bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED; + + /* + * 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) || disconnected)) + 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); } |