ovl_writeout() relies on the workdir i_rwsem to provide exclusive access
to ofs->writeout which it manipulates. Rather than depending on this,
add a new mutex, "writeout_lock" to explicitly provide the required
locking.
Then take the lock on workdir only when needed - to lookup the temp name
and to do the whiteout or link. So ovl_writeout() and similarly
ovl_cleanup_and_writeout() and ovl_workdir_cleanup() are now called
without the lock held. This requires changes to
ovl_remove_and_whiteout(), ovl_cleanup_index(), ovl_indexdir_cleanup(),
and ovl_workdir_create().
Signed-off-by: NeilBrown <neil@xxxxxxxxxx>
---
fs/overlayfs/dir.c | 71 +++++++++++++++++++++-------------------
fs/overlayfs/overlayfs.h | 2 +-
fs/overlayfs/ovl_entry.h | 1 +
fs/overlayfs/params.c | 2 ++
fs/overlayfs/readdir.c | 31 ++++++++++--------
fs/overlayfs/super.c | 9 +++--
fs/overlayfs/util.c | 7 ++--
7 files changed, 67 insertions(+), 56 deletions(-)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 5afe17cee305..78b0d956b0ac 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -77,7 +77,6 @@ struct dentry *ovl_lookup_temp(struct ovl_fs *ofs, struct dentry *workdir)
return temp;
}
-/* caller holds i_mutex on workdir */
static struct dentry *ovl_whiteout(struct ovl_fs *ofs)
{
int err;
@@ -85,47 +84,51 @@ static struct dentry *ovl_whiteout(struct ovl_fs *ofs)
struct dentry *workdir = ofs->workdir;
struct inode *wdir = workdir->d_inode;
+ mutex_lock(&ofs->whiteout_lock);
if (!ofs->whiteout) {
+ inode_lock(wdir);
whiteout = ovl_lookup_temp(ofs, workdir);
+ if (!IS_ERR(whiteout)) {
+ err = ovl_do_whiteout(ofs, wdir, whiteout);
+ if (err) {
+ dput(whiteout);
+ whiteout = ERR_PTR(err);
+ }
+ }
+ inode_unlock(wdir);
if (IS_ERR(whiteout))
goto out;
-
- err = ovl_do_whiteout(ofs, wdir, whiteout);
- if (err) {
- dput(whiteout);
- whiteout = ERR_PTR(err);
- goto out;
- }
ofs->whiteout = whiteout;
}
if (!ofs->no_shared_whiteout) {
+ inode_lock(wdir);
whiteout = ovl_lookup_temp(ofs, workdir);
- if (IS_ERR(whiteout))
- goto out;
-
- err = ovl_do_link(ofs, ofs->whiteout, wdir, whiteout);
- if (!err)
+ if (!IS_ERR(whiteout)) {
+ err = ovl_do_link(ofs, ofs->whiteout, wdir, whiteout);
+ if (err) {
+ dput(whiteout);
+ whiteout = ERR_PTR(err);
+ }
+ }
+ inode_unlock(wdir);
+ if (!IS_ERR(whiteout) || PTR_ERR(whiteout) != -EMLINK)
goto out;
- if (err != -EMLINK) {
- pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%i)\n",
- ofs->whiteout->d_inode->i_nlink, err);
- ofs->no_shared_whiteout = true;
- }
- dput(whiteout);
+ pr_warn("Failed to link whiteout - disabling whiteout inode sharing(nlink=%u, err=%i)\n",
+ ofs->whiteout->d_inode->i_nlink, err);
+ ofs->no_shared_whiteout = true;
}
whiteout = ofs->whiteout;
ofs->whiteout = NULL;
out:
+ mutex_unlock(&ofs->whiteout_lock);
return whiteout;
}
-/* Caller must hold i_mutex on both workdir and dir */
int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct dentry *dir,
struct dentry *dentry)
{
- struct inode *wdir = ofs->workdir->d_inode;
struct dentry *whiteout;
int err;
int flags = 0;
@@ -138,18 +141,26 @@ int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct dentry *dir,
if (d_is_dir(dentry))
flags = RENAME_EXCHANGE;
- err = ovl_do_rename(ofs, ofs->workdir, whiteout, dir, dentry, flags);
+ err = ovl_lock_rename_workdir(ofs->workdir, dir);
+ if (!err) {
+ if (whiteout->d_parent == ofs->workdir)
+ err = ovl_do_rename(ofs, ofs->workdir, whiteout, dir,
+ dentry, flags);
+ else
+ err = -EINVAL;
+ unlock_rename(ofs->workdir, dir);
+ }
if (err)
goto kill_whiteout;
if (flags)
- ovl_cleanup(ofs, wdir, dentry);
+ ovl_cleanup_unlocked(ofs, ofs->workdir, dentry);
out:
dput(whiteout);
return err;
kill_whiteout:
- ovl_cleanup(ofs, wdir, whiteout);
+ ovl_cleanup_unlocked(ofs, ofs->workdir, whiteout);
goto out;
}
@@ -777,15 +788,11 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
goto out;
}
- err = ovl_lock_rename_workdir(workdir, upperdir);
- if (err)
- goto out_dput;
-
- upper = ovl_lookup_upper(ofs, dentry->d_name.name, upperdir,
- dentry->d_name.len);
+ upper = ovl_lookup_upper_unlocked(ofs, dentry->d_name.name, upperdir,
+ dentry->d_name.len);
err = PTR_ERR(upper);
if (IS_ERR(upper))
- goto out_unlock;
+ goto out_dput;
err = -ESTALE;
if ((opaquedir && upper != opaquedir) ||
@@ -803,8 +810,6 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
d_drop(dentry);
out_dput_upper:
dput(upper);
-out_unlock:
- unlock_rename(workdir, upperdir);
out_dput:
dput(opaquedir);
out:
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 508003e26e08..25378b81251e 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -732,7 +732,7 @@ void ovl_cleanup_whiteouts(struct ovl_fs *ofs, struct dentry *upper,
void ovl_cache_free(struct list_head *list);
void ovl_dir_cache_free(struct inode *inode);
int ovl_check_d_type_supported(const struct path *realpath);
-int ovl_workdir_cleanup(struct ovl_fs *ofs, struct inode *dir,
+int ovl_workdir_cleanup(struct ovl_fs *ofs, struct dentry *parent,
struct vfsmount *mnt, struct dentry *dentry, int level);
int ovl_indexdir_cleanup(struct ovl_fs *ofs);
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index afb7762f873f..4c1bae935ced 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -88,6 +88,7 @@ struct ovl_fs {
/* Shared whiteout cache */
struct dentry *whiteout;
bool no_shared_whiteout;
+ struct mutex whiteout_lock;
/* r/o snapshot of upperdir sb's only taken on volatile mounts */
errseq_t errseq;
};
diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index f42488c01957..cb1a17c066cd 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -797,6 +797,8 @@ int ovl_init_fs_context(struct fs_context *fc)
fc->s_fs_info = ofs;
fc->fs_private = ctx;
fc->ops = &ovl_context_ops;
+
+ mutex_init(&ofs->whiteout_lock);
return 0;
out_err:
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 2a222b8185a3..fd98444dacef 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -1141,7 +1141,8 @@ static int ovl_workdir_cleanup_recurse(struct ovl_fs *ofs, const struct path *pa
if (IS_ERR(dentry))
continue;
if (dentry->d_inode)
- err = ovl_workdir_cleanup(ofs, dir, path->mnt, dentry, level);
+ err = ovl_workdir_cleanup(ofs, path->dentry, path->mnt,
+ dentry, level);
dput(dentry);
if (err)
break;
@@ -1152,24 +1153,27 @@ static int ovl_workdir_cleanup_recurse(struct ovl_fs *ofs, const struct path *pa
return err;
}
-int ovl_workdir_cleanup(struct ovl_fs *ofs, struct inode *dir,
+int ovl_workdir_cleanup(struct ovl_fs *ofs, struct dentry *parent,
struct vfsmount *mnt, struct dentry *dentry, int level)
{
int err;
if (!d_is_dir(dentry) || level > 1) {
- return ovl_cleanup(ofs, dir, dentry);
+ return ovl_cleanup_unlocked(ofs, parent, dentry);
}
- err = ovl_do_rmdir(ofs, dir, dentry);
+ inode_lock_nested(parent->d_inode, I_MUTEX_PARENT);
+ if (dentry->d_parent == parent)
+ err = ovl_do_rmdir(ofs, parent->d_inode, dentry);
+ else
+ err = -EINVAL;
+ inode_unlock(parent->d_inode);
if (err) {
struct path path = { .mnt = mnt, .dentry = dentry };
- inode_unlock(dir);
err = ovl_workdir_cleanup_recurse(ofs, &path, level + 1);
- inode_lock_nested(dir, I_MUTEX_PARENT);
if (!err)
- err = ovl_cleanup(ofs, dir, dentry);
+ err = ovl_cleanup_unlocked(ofs, parent, dentry);
}
return err;
@@ -1180,7 +1184,6 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
int err;
struct dentry *indexdir = ofs->workdir;
struct dentry *index = NULL;
- struct inode *dir = indexdir->d_inode;
struct path path = { .mnt = ovl_upper_mnt(ofs), .dentry = indexdir };
LIST_HEAD(list);
struct ovl_cache_entry *p;
@@ -1194,7 +1197,6 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
if (err)
goto out;
- inode_lock_nested(dir, I_MUTEX_PARENT);
list_for_each_entry(p, &list, l_node) {
if (p->name[0] == '.') {
if (p->len == 1)
@@ -1202,7 +1204,8 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
if (p->len == 2 && p->name[1] == '.')
continue;
}
- index = ovl_lookup_upper(ofs, p->name, indexdir, p->len);
+ index = ovl_lookup_upper_unlocked(ofs, p->name, indexdir,
+ p->len);
if (IS_ERR(index)) {
err = PTR_ERR(index);
index = NULL;
@@ -1210,7 +1213,8 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
}
/* Cleanup leftover from index create/cleanup attempt */
if (index->d_name.name[0] == '#') {
- err = ovl_workdir_cleanup(ofs, dir, path.mnt, index, 1);
+ err = ovl_workdir_cleanup(ofs, indexdir, path.mnt,
+ index, 1);
if (err)
break;
goto next;
@@ -1220,7 +1224,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
goto next;
} else if (err == -ESTALE) {
/* Cleanup stale index entries */
- err = ovl_cleanup(ofs, dir, index);
+ err = ovl_cleanup_unlocked(ofs, indexdir, index);
} else if (err != -ENOENT) {
/*
* Abort mount to avoid corrupting the index if
@@ -1236,7 +1240,7 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
err = ovl_cleanup_and_whiteout(ofs, indexdir, index);
} else {
/* Cleanup orphan index entries */
- err = ovl_cleanup(ofs, dir, index);
+ err = ovl_cleanup_unlocked(ofs, indexdir, index);
}
if (err)
@@ -1247,7 +1251,6 @@ int ovl_indexdir_cleanup(struct ovl_fs *ofs)
index = NULL;
}
dput(index);
- inode_unlock(dir);
out:
ovl_cache_free(&list);
if (err)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 576b5c3b537c..3583e359655f 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -299,8 +299,8 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
int err;
bool retried = false;
- inode_lock_nested(dir, I_MUTEX_PARENT);
retry:
+ inode_lock_nested(dir, I_MUTEX_PARENT);
work = ovl_lookup_upper(ofs, name, ofs->workbasedir, strlen(name));
if (!IS_ERR(work)) {
@@ -311,6 +311,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
if (work->d_inode) {
err = -EEXIST;
+ inode_unlock(dir);
if (retried)
goto out_dput;
@@ -318,7 +319,8 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
goto out_unlock;
retried = true;
- err = ovl_workdir_cleanup(ofs, dir, mnt, work, 0);
+ err = ovl_workdir_cleanup(ofs, ofs->workbasedir, mnt,
+ work, 0);
dput(work);
if (err == -EINVAL) {
work = ERR_PTR(err);
@@ -328,6 +330,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
}
work = ovl_do_mkdir(ofs, dir, work, attr.ia_mode);
+ inode_unlock(dir);
err = PTR_ERR(work);
if (IS_ERR(work))
goto out_err;
@@ -365,11 +368,11 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
if (err)
goto out_dput;
} else {
+ inode_unlock(dir);
err = PTR_ERR(work);
goto out_err;
}
out_unlock:
- inode_unlock(dir);
return work;
out_dput:
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 2b4754c645ee..565f7d8c0147 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -1071,7 +1071,6 @@ static void ovl_cleanup_index(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
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;
@@ -1107,8 +1106,7 @@ static void ovl_cleanup_index(struct dentry *dentry)
goto out;
}
- inode_lock_nested(dir, I_MUTEX_PARENT);
- index = ovl_lookup_upper(ofs, name.name, indexdir, name.len);
+ index = ovl_lookup_upper_unlocked(ofs, name.name, indexdir, name.len);
err = PTR_ERR(index);
if (IS_ERR(index)) {
index = NULL;
@@ -1118,10 +1116,9 @@ static void ovl_cleanup_index(struct dentry *dentry)
indexdir, index);
} else {
/* Cleanup orphan index entries */
- err = ovl_cleanup(ofs, dir, index);
+ err = ovl_cleanup_unlocked(ofs, indexdir, index);
}
- inode_unlock(dir);
if (err)
goto fail;
--
2.49.0
