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ovl: whiteout index when union nlink drops to zero 

With NFS export feature enabled, when overlay inode nlink drops to
zero, instead of removing the index entry, replace it with a whiteout
index entry.

This is needed for NFS export in order to prevent future open by handle
from opening the lower file directly.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2017-10-24 17:38:33 +03:00 committed by Miklos Szeredi
parent 89a17556ce
commit e7dd0e7134
3 changed files with 48 additions and 29 deletions
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58
fs/overlayfs/dir.c
View File

@ -63,8 +63,7 @@ struct dentry *ovl_lookup_temp(struct dentry *workdir)
}
/* caller holds i_mutex on workdir */
static struct dentry *ovl_whiteout(struct dentry *workdir,
struct dentry *dentry)
static struct dentry *ovl_whiteout(struct dentry *workdir)
{
int err;
struct dentry *whiteout;
@ -83,6 +82,38 @@ static struct dentry *ovl_whiteout(struct dentry *workdir,
return whiteout;
}
/* Caller must hold i_mutex on both workdir and dir */
int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
struct dentry *dentry)
{
struct inode *wdir = workdir->d_inode;
struct dentry *whiteout;
int err;
int flags = 0;
whiteout = ovl_whiteout(workdir);
err = PTR_ERR(whiteout);
if (IS_ERR(whiteout))
return err;
if (d_is_dir(dentry))
flags = RENAME_EXCHANGE;
err = ovl_do_rename(wdir, whiteout, dir, dentry, flags);
if (err)
goto kill_whiteout;
if (flags)
ovl_cleanup(wdir, dentry);
out:
dput(whiteout);
return err;
kill_whiteout:
ovl_cleanup(wdir, whiteout);
goto out;
}
int ovl_create_real(struct inode *dir, struct dentry *newdentry,
struct cattr *attr, struct dentry *hardlink, bool debug)
{
@ -591,14 +622,10 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
struct list_head *list)
{
struct dentry *workdir = ovl_workdir(dentry);
struct inode *wdir = workdir->d_inode;
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
struct inode *udir = upperdir->d_inode;
struct dentry *whiteout;
struct dentry *upper;
struct dentry *opaquedir = NULL;
int err;
int flags = 0;
if (WARN_ON(!workdir))
return -EROFS;
@ -627,24 +654,13 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
goto out_dput_upper;
}
whiteout = ovl_whiteout(workdir, dentry);
err = PTR_ERR(whiteout);
if (IS_ERR(whiteout))
goto out_dput_upper;
if (d_is_dir(upper))
flags = RENAME_EXCHANGE;
err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
err = ovl_cleanup_and_whiteout(workdir, d_inode(upperdir), upper);
if (err)
goto kill_whiteout;
if (flags)
ovl_cleanup(wdir, upper);
goto out_d_drop;
ovl_dentry_version_inc(dentry->d_parent, true);
out_d_drop:
d_drop(dentry);
dput(whiteout);
out_dput_upper:
dput(upper);
out_unlock:
@ -653,10 +669,6 @@ out_dput:
dput(opaquedir);
out:
return err;
kill_whiteout:
ovl_cleanup(wdir, whiteout);
goto out_d_drop;
}
static int ovl_remove_upper(struct dentry *dentry, bool is_dir,

2
fs/overlayfs/overlayfs.h
View File

@ -321,6 +321,8 @@ static inline void ovl_copyattr(struct inode *from, struct inode *to)
/* dir.c */
extern const struct inode_operations ovl_dir_inode_operations;
struct dentry *ovl_lookup_temp(struct dentry *workdir);
int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
struct dentry *dentry);
struct cattr {
dev_t rdev;
umode_t mode;

17
fs/overlayfs/util.c
View File

@ -487,7 +487,8 @@ bool ovl_need_index(struct dentry *dentry)
/* Caller must hold OVL_I(inode)->lock */
static void ovl_cleanup_index(struct dentry *dentry)
{
struct inode *dir = ovl_indexdir(dentry->d_sb)->d_inode;
struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
struct inode *dir = indexdir->d_inode;
struct dentry *lowerdentry = ovl_dentry_lower(dentry);
struct dentry *upperdentry = ovl_dentry_upper(dentry);
struct dentry *index = NULL;
@ -518,13 +519,17 @@ static void ovl_cleanup_index(struct dentry *dentry)
}
inode_lock_nested(dir, I_MUTEX_PARENT);
/* TODO: whiteout instead of cleanup to block future open by handle */
index = lookup_one_len(name.name, ovl_indexdir(dentry->d_sb), name.len);
index = lookup_one_len(name.name, indexdir, name.len);
err = PTR_ERR(index);
if (!IS_ERR(index))
err = ovl_cleanup(dir, index);
else
if (IS_ERR(index)) {
index = NULL;
} else if (ovl_index_all(dentry->d_sb)) {
/* Whiteout orphan index to block future open by handle */
err = ovl_cleanup_and_whiteout(indexdir, dir, index);
} else {
/* Cleanup orphan index entries */
err = ovl_cleanup(dir, index);
}
inode_unlock(dir);
if (err)