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fs/9p: fixes for 6.9-rc6

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Contains a single mitigation to help deal with an apparent
 race condition between client and server having to deal with
 inode number collisions.
 
 Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
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Merge tag '9p-for-6.9-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs

Pull 9p fix from Eric Van Hensbergen:
 "This contains a single mitigation to help deal with an apparent race
  condition between client and server having to deal with inode number
  collisions"

* tag '9p-for-6.9-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh/v9fs:
  fs/9p: mitigate inode collisions
This commit is contained in:
Linus Torvalds 2024-04-25 15:31:56 -07:00
commit dda89e2fbc
4 changed files with 56 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
fs/9p/v9fs.h
View File

@ -179,13 +179,14 @@ extern int v9fs_vfs_rename(struct mnt_idmap *idmap,
struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags);
extern struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid);
extern struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid,
bool new);
extern const struct inode_operations v9fs_dir_inode_operations_dotl;
extern const struct inode_operations v9fs_file_inode_operations_dotl;
extern const struct inode_operations v9fs_symlink_inode_operations_dotl;
extern const struct netfs_request_ops v9fs_req_ops;
extern struct inode *v9fs_fid_iget_dotl(struct super_block *sb,
struct p9_fid *fid);
struct p9_fid *fid, bool new);
/* other default globals */
#define V9FS_PORT 564
@ -224,12 +225,12 @@ static inline int v9fs_proto_dotl(struct v9fs_session_info *v9ses)
*/
static inline struct inode *
v9fs_get_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
struct super_block *sb)
struct super_block *sb, bool new)
{
if (v9fs_proto_dotl(v9ses))
return v9fs_fid_iget_dotl(sb, fid);
return v9fs_fid_iget_dotl(sb, fid, new);
else
return v9fs_fid_iget(sb, fid);
return v9fs_fid_iget(sb, fid, new);
}
#endif

37
fs/9p/vfs_inode.c
View File

@ -364,7 +364,8 @@ void v9fs_evict_inode(struct inode *inode)
clear_inode(inode);
}
struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid)
struct inode *
v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid, bool new)
{
dev_t rdev;
int retval;
@ -376,8 +377,18 @@ struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid)
inode = iget_locked(sb, QID2INO(&fid->qid));
if (unlikely(!inode))
return ERR_PTR(-ENOMEM);
if (!(inode->i_state & I_NEW))
return inode;
if (!(inode->i_state & I_NEW)) {
if (!new) {
goto done;
} else {
p9_debug(P9_DEBUG_VFS, "WARNING: Inode collision %ld\n",
inode->i_ino);
iput(inode);
remove_inode_hash(inode);
inode = iget_locked(sb, QID2INO(&fid->qid));
WARN_ON(!(inode->i_state & I_NEW));
}
}
/*
* initialize the inode with the stat info
@ -401,11 +412,11 @@ struct inode *v9fs_fid_iget(struct super_block *sb, struct p9_fid *fid)
v9fs_set_netfs_context(inode);
v9fs_cache_inode_get_cookie(inode);
unlock_new_inode(inode);
done:
return inode;
error:
iget_failed(inode);
return ERR_PTR(retval);
}
/**
@ -437,8 +448,15 @@ static int v9fs_at_to_dotl_flags(int flags)
*/
static void v9fs_dec_count(struct inode *inode)
{
if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2)
drop_nlink(inode);
if (!S_ISDIR(inode->i_mode) || inode->i_nlink > 2) {
if (inode->i_nlink) {
drop_nlink(inode);
} else {
p9_debug(P9_DEBUG_VFS,
"WARNING: unexpected i_nlink zero %d inode %ld\n",
inode->i_nlink, inode->i_ino);
}
}
}
/**
@ -489,6 +507,9 @@ static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
} else
v9fs_dec_count(inode);
if (inode->i_nlink <= 0) /* no more refs unhash it */
remove_inode_hash(inode);
v9fs_invalidate_inode_attr(inode);
v9fs_invalidate_inode_attr(dir);
@ -554,7 +575,7 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
/*
* instantiate inode and assign the unopened fid to the dentry
*/
inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb, true);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
p9_debug(P9_DEBUG_VFS,
@ -683,7 +704,7 @@ struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
else if (IS_ERR(fid))
inode = ERR_CAST(fid);
else
inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb, false);
/*
* If we had a rename on the server and a parallel lookup
* for the new name, then make sure we instantiate with

28
fs/9p/vfs_inode_dotl.c
View File

@ -52,7 +52,10 @@ static kgid_t v9fs_get_fsgid_for_create(struct inode *dir_inode)
return current_fsgid();
}
struct inode *v9fs_fid_iget_dotl(struct super_block *sb, struct p9_fid *fid)
struct inode *
v9fs_fid_iget_dotl(struct super_block *sb, struct p9_fid *fid, bool new)
{
int retval;
struct inode *inode;
@ -62,8 +65,18 @@ struct inode *v9fs_fid_iget_dotl(struct super_block *sb, struct p9_fid *fid)
inode = iget_locked(sb, QID2INO(&fid->qid));
if (unlikely(!inode))
return ERR_PTR(-ENOMEM);
if (!(inode->i_state & I_NEW))
return inode;
if (!(inode->i_state & I_NEW)) {
if (!new) {
goto done;
} else { /* deal with race condition in inode number reuse */
p9_debug(P9_DEBUG_ERROR, "WARNING: Inode collision %lx\n",
inode->i_ino);
iput(inode);
remove_inode_hash(inode);
inode = iget_locked(sb, QID2INO(&fid->qid));
WARN_ON(!(inode->i_state & I_NEW));
}
}
/*
* initialize the inode with the stat info
@ -90,12 +103,11 @@ struct inode *v9fs_fid_iget_dotl(struct super_block *sb, struct p9_fid *fid)
goto error;
unlock_new_inode(inode);
done:
return inode;
error:
iget_failed(inode);
return ERR_PTR(retval);
}
struct dotl_openflag_map {
@ -247,7 +259,7 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
goto out;
}
inode = v9fs_fid_iget_dotl(dir->i_sb, fid);
inode = v9fs_fid_iget_dotl(dir->i_sb, fid, true);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
p9_debug(P9_DEBUG_VFS, "inode creation failed %d\n", err);
@ -340,7 +352,7 @@ static int v9fs_vfs_mkdir_dotl(struct mnt_idmap *idmap,
}
/* instantiate inode and assign the unopened fid to the dentry */
inode = v9fs_fid_iget_dotl(dir->i_sb, fid);
inode = v9fs_fid_iget_dotl(dir->i_sb, fid, true);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
p9_debug(P9_DEBUG_VFS, "inode creation failed %d\n",
@ -776,7 +788,7 @@ v9fs_vfs_mknod_dotl(struct mnt_idmap *idmap, struct inode *dir,
err);
goto error;
}
inode = v9fs_fid_iget_dotl(dir->i_sb, fid);
inode = v9fs_fid_iget_dotl(dir->i_sb, fid, true);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
p9_debug(P9_DEBUG_VFS, "inode creation failed %d\n",

2
fs/9p/vfs_super.c
View File

@ -139,7 +139,7 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
else
sb->s_d_op = &v9fs_dentry_operations;
inode = v9fs_get_inode_from_fid(v9ses, fid, sb);
inode = v9fs_get_inode_from_fid(v9ses, fid, sb, true);
if (IS_ERR(inode)) {
retval = PTR_ERR(inode);
goto release_sb;