Currently ovl_get_inode() initializes OVL_UPPERDATA flag and for that it
has to call ovl_check_metacopy_xattr() and check if metacopy xattr is
present or not.
yangerkun reported sometimes underlying filesystem might return -EIO
and in that case error handling path does not cleanup properly leading
to various warnings.
Run generic/461 with ext4 upper/lower layer sometimes may trigger the
bug as below(linux 4.19):
[ 551.001349] overlayfs: failed to get metacopy (-5)
[ 551.003464] overlayfs: failed to get inode (-5)
[ 551.004243] overlayfs: cleanup of 'd44/fd51' failed (-5)
[ 551.004941] overlayfs: failed to get origin (-5)
[ 551.005199] ------------[ cut here ]------------
[ 551.006697] WARNING: CPU: 3 PID: 24674 at fs/inode.c:1528 iput+0x33b/0x400
...
[ 551.027219] Call Trace:
[ 551.027623] ovl_create_object+0x13f/0x170
[ 551.028268] ovl_create+0x27/0x30
[ 551.028799] path_openat+0x1a35/0x1ea0
[ 551.029377] do_filp_open+0xad/0x160
[ 551.029944] ? vfs_writev+0xe9/0x170
[ 551.030499] ? page_counter_try_charge+0x77/0x120
[ 551.031245] ? __alloc_fd+0x160/0x2a0
[ 551.031832] ? do_sys_open+0x189/0x340
[ 551.032417] ? get_unused_fd_flags+0x34/0x40
[ 551.033081] do_sys_open+0x189/0x340
[ 551.033632] __x64_sys_creat+0x24/0x30
[ 551.034219] do_syscall_64+0xd5/0x430
[ 551.034800] entry_SYSCALL_64_after_hwframe+0x44/0xa9
One solution is to improve error handling and call iget_failed() if error
is encountered. Amir thinks that this path is little intricate and there
is not real need to check and initialize OVL_UPPERDATA in ovl_get_inode().
Instead caller of ovl_get_inode() can initialize this state. And this
will avoid double checking of metacopy xattr lookup in ovl_lookup()
and ovl_get_inode().
OVL_UPPERDATA is inode flag. So I was little concerned that initializing
it outside ovl_get_inode() might have some races. But this is one way
transition. That is once a file has been fully copied up, it can't go
back to metacopy file again. And that seems to help avoid races. So
as of now I can't see any races w.r.t OVL_UPPERDATA being set wrongly. So
move settingof OVL_UPPERDATA inside the callers of ovl_get_inode().
ovl_obtain_alias() already does it. So only two callers now left
are ovl_lookup() and ovl_instantiate().
Reported-by: yangerkun <yangerkun@xxxxxxxxxx>
Suggested-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
fs/overlayfs/dir.c | 2 ++
fs/overlayfs/inode.c | 11 +----------
fs/overlayfs/namei.c | 2 ++
3 files changed, 5 insertions(+), 10 deletions(-)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 279009dee366..a7cac2ce0fad 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -262,6 +262,8 @@ static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
inode = ovl_get_inode(dentry->d_sb, &oip);
if (IS_ERR(inode))
return PTR_ERR(inode);
+ if (inode == oip.newinode)
+ ovl_set_flag(OVL_UPPERDATA, inode);
} else {
WARN_ON(ovl_inode_real(inode) != d_inode(newdentry));
dput(newdentry);
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 981f11ec51bc..f2aaf00821c0 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -957,7 +957,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry,
oip->index);
int fsid = bylower ? lowerpath->layer->fsid : 0;
- bool is_dir, metacopy = false;
+ bool is_dir;
unsigned long ino = 0;
int err = oip->newinode ? -EEXIST : -ENOMEM;
@@ -1018,15 +1018,6 @@ struct inode *ovl_get_inode(struct super_block *sb,
if (oip->index)
ovl_set_flag(OVL_INDEX, inode);
- if (upperdentry) {
- err = ovl_check_metacopy_xattr(upperdentry);
- if (err < 0)
- goto out_err;
- metacopy = err;
- if (!metacopy)
- ovl_set_flag(OVL_UPPERDATA, inode);
- }
-
OVL_I(inode)->redirect = oip->redirect;
if (bylower)
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index a1889a160708..36e2b88a2fd1 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -1078,6 +1078,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
err = PTR_ERR(inode);
if (IS_ERR(inode))
goto out_free_oe;
+ if (upperdentry && !uppermetacopy)
+ ovl_set_flag(OVL_UPPERDATA, inode);
}
ovl_dentry_update_reval(dentry, upperdentry,
--
2.25.4
