This patch can ensure that loop devices based on erofs and overlayfs
can't set dio through __loop_update_dio.
Tested-by: Huang Jianan <huangjianan@xxxxxxxx>
Thanks,
Jianan
在 2021/9/28 20:47, Chengguang Xu 写道:
Loop device checks the ability of DIRECT-IO by checking
a_ops->direct_IO of inode, in order to avoid this kind of
false detection we set a_ops->direct_IO for overlayfs inode
only when underlying inode really has DIRECT-IO ability.
Reported-by: Huang Jianan <huangjianan@xxxxxxxx>
Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxxxx>
---
fs/overlayfs/dir.c | 2 ++
fs/overlayfs/inode.c | 4 ++--
fs/overlayfs/overlayfs.h | 1 +
fs/overlayfs/util.c | 14 ++++++++++++++
4 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 1fefb2b8960e..32a60f9e3f9e 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -648,6 +648,8 @@ static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
/* Did we end up using the preallocated inode? */
if (inode != d_inode(dentry))
iput(inode);
+ else
+ ovl_inode_set_aops(inode);
out_drop_write:
ovl_drop_write(dentry);
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 832b17589733..a7a327e4f790 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -659,7 +659,7 @@ static const struct inode_operations ovl_special_inode_operations = {
.update_time = ovl_update_time,
};
-static const struct address_space_operations ovl_aops = {
+const struct address_space_operations ovl_aops = {
/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
.direct_IO = noop_direct_IO,
};
@@ -786,6 +786,7 @@ void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
ovl_copyattr(realinode, inode);
ovl_copyflags(realinode, inode);
ovl_map_ino(inode, ino, fsid);
+ ovl_inode_set_aops(inode);
}
static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev)
@@ -802,7 +803,6 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev)
case S_IFREG:
inode->i_op = &ovl_file_inode_operations;
inode->i_fop = &ovl_file_operations;
- inode->i_mapping->a_ops = &ovl_aops;
break;
case S_IFDIR:
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 3894f3347955..976c9d634293 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -349,6 +349,7 @@ bool ovl_is_metacopy_dentry(struct dentry *dentry);
char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct dentry *dentry,
int padding);
int ovl_sync_status(struct ovl_fs *ofs);
+void ovl_inode_set_aops(struct inode *inode);
static inline void ovl_set_flag(unsigned long flag, struct inode *inode)
{
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index f48284a2a896..33535dbee1c3 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -1060,3 +1060,17 @@ int ovl_sync_status(struct ovl_fs *ofs)
return errseq_check(&mnt->mnt_sb->s_wb_err, ofs->errseq);
}
+
+extern const struct address_space_operations ovl_aops;
+void ovl_inode_set_aops(struct inode *inode)
+{
+ struct inode *realinode;
+
+ if (!S_ISREG(inode->i_mode))
+ return;
+
+ realinode = ovl_inode_realdata(inode);
+ if (realinode && realinode->i_mapping && realinode->i_mapping->a_ops &&
+ realinode->i_mapping->a_ops->direct_IO)
+ inode->i_mapping->a_ops = &ovl_aops;
+}
