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ovl: create ovl_need_index() helper 

The helper determines which lower file needs to be indexed
on copy up and before nlink changes.

For index=on, the helper evaluates to true for lower hardlinks.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2017-09-26 07:55:26 +03:00 committed by Miklos Szeredi
parent 9ee60ce249
commit 24b33ee104
3 changed files with 22 additions and 9 deletions
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6
fs/overlayfs/copy_up.c
View File

@ -536,11 +536,7 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
{
int err;
struct ovl_fs *ofs = c->dentry->d_sb->s_fs_info;
bool indexed = false;
if (ovl_indexdir(c->dentry->d_sb) && !S_ISDIR(c->stat.mode) &&
c->stat.nlink > 1)
indexed = true;
bool indexed = ovl_need_index(c->dentry);
if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || indexed)
c->origin = true;

1
fs/overlayfs/overlayfs.h
View File

@ -241,6 +241,7 @@ void ovl_clear_flag(unsigned long flag, struct inode *inode);
bool ovl_test_flag(unsigned long flag, struct inode *inode);
bool ovl_inuse_trylock(struct dentry *dentry);
void ovl_inuse_unlock(struct dentry *dentry);
bool ovl_need_index(struct dentry *dentry);
int ovl_nlink_start(struct dentry *dentry, bool *locked);
void ovl_nlink_end(struct dentry *dentry, bool locked);
int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);

24
fs/overlayfs/util.c
View File

@ -463,6 +463,23 @@ void ovl_inuse_unlock(struct dentry *dentry)
}
}
/*
* Does this overlay dentry need to be indexed on copy up?
*/
bool ovl_need_index(struct dentry *dentry)
{
struct dentry *lower = ovl_dentry_lower(dentry);
if (!lower || !ovl_indexdir(dentry->d_sb))
return false;
/* Index only lower hardlinks on copy up */
if (!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
return true;
return false;
}
/* Caller must hold OVL_I(inode)->lock */
static void ovl_cleanup_index(struct dentry *dentry)
{
@ -533,11 +550,11 @@ int ovl_nlink_start(struct dentry *dentry, bool *locked)
/*
* With inodes index is enabled, we store the union overlay nlink
* in an xattr on the index inode. When whiting out lower hardlinks
* in an xattr on the index inode. When whiting out an indexed lower,
* we need to decrement the overlay persistent nlink, but before the
* first copy up, we have no upper index inode to store the xattr.
*
* As a workaround, before whiteout/rename over of a lower hardlink,
* As a workaround, before whiteout/rename over an indexed lower,
* copy up to create the upper index. Creating the upper index will
* initialize the overlay nlink, so it could be dropped if unlink
* or rename succeeds.
@ -545,8 +562,7 @@ int ovl_nlink_start(struct dentry *dentry, bool *locked)
* TODO: implement metadata only index copy up when called with
* ovl_copy_up_flags(dentry, O_PATH).
*/
if (ovl_indexdir(dentry->d_sb) && !ovl_dentry_has_upper_alias(dentry) &&
d_inode(ovl_dentry_lower(dentry))->i_nlink > 1) {
if (ovl_need_index(dentry) && !ovl_dentry_has_upper_alias(dentry)) {
err = ovl_copy_up(dentry);
if (err)
return err;