From cc3ddee97cff034cea4d095de4a484c92a219bf5 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Thu, 21 Jan 2021 10:08:59 +0100 Subject: [PATCH 1/4] vboxsf: Honor excl flag to the dir-inode create op Honor the excl flag to the dir-inode create op, instead of behaving as if it is always set. Note the old behavior still worked most of the time since a non-exclusive open only calls the create op, if there is a race and the file is created between the dentry lookup and the calling of the create call. While at it change the type of the is_dir parameter to the vboxsf_dir_create() helper from an int to a bool, to be consistent with the use of bool for the excl parameter. Fixes: 0fd169576648 ("fs: Add VirtualBox guest shared folder (vboxsf) support") Signed-off-by: Hans de Goede --- fs/vboxsf/dir.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/fs/vboxsf/dir.c b/fs/vboxsf/dir.c index eac6788fc6cff..6ff84343edcad 100644 --- a/fs/vboxsf/dir.c +++ b/fs/vboxsf/dir.c @@ -253,7 +253,7 @@ static int vboxsf_dir_instantiate(struct inode *parent, struct dentry *dentry, } static int vboxsf_dir_create(struct inode *parent, struct dentry *dentry, - umode_t mode, int is_dir) + umode_t mode, bool is_dir, bool excl) { struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent); struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb); @@ -261,10 +261,12 @@ static int vboxsf_dir_create(struct inode *parent, struct dentry *dentry, int err; params.handle = SHFL_HANDLE_NIL; - params.create_flags = SHFL_CF_ACT_CREATE_IF_NEW | - SHFL_CF_ACT_FAIL_IF_EXISTS | - SHFL_CF_ACCESS_READWRITE | - (is_dir ? SHFL_CF_DIRECTORY : 0); + params.create_flags = SHFL_CF_ACT_CREATE_IF_NEW | SHFL_CF_ACCESS_READWRITE; + if (is_dir) + params.create_flags |= SHFL_CF_DIRECTORY; + if (excl) + params.create_flags |= SHFL_CF_ACT_FAIL_IF_EXISTS; + params.info.attr.mode = (mode & 0777) | (is_dir ? SHFL_TYPE_DIRECTORY : SHFL_TYPE_FILE); params.info.attr.additional = SHFLFSOBJATTRADD_NOTHING; @@ -292,14 +294,14 @@ static int vboxsf_dir_mkfile(struct user_namespace *mnt_userns, struct inode *parent, struct dentry *dentry, umode_t mode, bool excl) { - return vboxsf_dir_create(parent, dentry, mode, 0); + return vboxsf_dir_create(parent, dentry, mode, false, excl); } static int vboxsf_dir_mkdir(struct user_namespace *mnt_userns, struct inode *parent, struct dentry *dentry, umode_t mode) { - return vboxsf_dir_create(parent, dentry, mode, 1); + return vboxsf_dir_create(parent, dentry, mode, true, true); } static int vboxsf_dir_unlink(struct inode *parent, struct dentry *dentry) From ab0c29687bc7a890d1a86ac376b0b0fd78b2d9b6 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Thu, 21 Jan 2021 10:22:27 +0100 Subject: [PATCH 2/4] vboxsf: Make vboxsf_dir_create() return the handle for the created file Make vboxsf_dir_create() optionally return the vboxsf-handle for the created file. This is a preparation patch for adding atomic_open support. Fixes: 0fd169576648 ("fs: Add VirtualBox guest shared folder (vboxsf) support") Signed-off-by: Hans de Goede --- fs/vboxsf/dir.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/fs/vboxsf/dir.c b/fs/vboxsf/dir.c index 6ff84343edcad..87d5b2fef592b 100644 --- a/fs/vboxsf/dir.c +++ b/fs/vboxsf/dir.c @@ -253,7 +253,7 @@ static int vboxsf_dir_instantiate(struct inode *parent, struct dentry *dentry, } static int vboxsf_dir_create(struct inode *parent, struct dentry *dentry, - umode_t mode, bool is_dir, bool excl) + umode_t mode, bool is_dir, bool excl, u64 *handle_ret) { struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent); struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb); @@ -278,30 +278,34 @@ static int vboxsf_dir_create(struct inode *parent, struct dentry *dentry, if (params.result != SHFL_FILE_CREATED) return -EPERM; - vboxsf_close(sbi->root, params.handle); - err = vboxsf_dir_instantiate(parent, dentry, ¶ms.info); if (err) - return err; + goto out; /* parent directory access/change time changed */ sf_parent_i->force_restat = 1; - return 0; +out: + if (err == 0 && handle_ret) + *handle_ret = params.handle; + else + vboxsf_close(sbi->root, params.handle); + + return err; } static int vboxsf_dir_mkfile(struct user_namespace *mnt_userns, struct inode *parent, struct dentry *dentry, umode_t mode, bool excl) { - return vboxsf_dir_create(parent, dentry, mode, false, excl); + return vboxsf_dir_create(parent, dentry, mode, false, excl, NULL); } static int vboxsf_dir_mkdir(struct user_namespace *mnt_userns, struct inode *parent, struct dentry *dentry, umode_t mode) { - return vboxsf_dir_create(parent, dentry, mode, true, true); + return vboxsf_dir_create(parent, dentry, mode, true, true, NULL); } static int vboxsf_dir_unlink(struct inode *parent, struct dentry *dentry) From 02f840f90764f22f5c898901849bdbf0cee752ba Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Thu, 21 Jan 2021 10:55:03 +0100 Subject: [PATCH 3/4] vboxsf: Add vboxsf_[create|release]_sf_handle() helpers Factor out the code to create / release a struct vboxsf_handle into 2 new helper functions. This is a preparation patch for adding atomic_open support. Fixes: 0fd169576648 ("fs: Add VirtualBox guest shared folder (vboxsf) support") Signed-off-by: Hans de Goede --- fs/vboxsf/file.c | 71 ++++++++++++++++++++++++++++------------------ fs/vboxsf/vfsmod.h | 7 +++++ 2 files changed, 51 insertions(+), 27 deletions(-) diff --git a/fs/vboxsf/file.c b/fs/vboxsf/file.c index c4ab5996d97a8..864c2fad23beb 100644 --- a/fs/vboxsf/file.c +++ b/fs/vboxsf/file.c @@ -20,17 +20,39 @@ struct vboxsf_handle { struct list_head head; }; -static int vboxsf_file_open(struct inode *inode, struct file *file) +struct vboxsf_handle *vboxsf_create_sf_handle(struct inode *inode, + u64 handle, u32 access_flags) { struct vboxsf_inode *sf_i = VBOXSF_I(inode); - struct shfl_createparms params = {}; struct vboxsf_handle *sf_handle; - u32 access_flags = 0; - int err; sf_handle = kmalloc(sizeof(*sf_handle), GFP_KERNEL); if (!sf_handle) - return -ENOMEM; + return ERR_PTR(-ENOMEM); + + /* the host may have given us different attr then requested */ + sf_i->force_restat = 1; + + /* init our handle struct and add it to the inode's handles list */ + sf_handle->handle = handle; + sf_handle->root = VBOXSF_SBI(inode->i_sb)->root; + sf_handle->access_flags = access_flags; + kref_init(&sf_handle->refcount); + + mutex_lock(&sf_i->handle_list_mutex); + list_add(&sf_handle->head, &sf_i->handle_list); + mutex_unlock(&sf_i->handle_list_mutex); + + return sf_handle; +} + +static int vboxsf_file_open(struct inode *inode, struct file *file) +{ + struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb); + struct shfl_createparms params = {}; + struct vboxsf_handle *sf_handle; + u32 access_flags = 0; + int err; /* * We check the value of params.handle afterwards to find out if @@ -83,23 +105,14 @@ static int vboxsf_file_open(struct inode *inode, struct file *file) err = vboxsf_create_at_dentry(file_dentry(file), ¶ms); if (err == 0 && params.handle == SHFL_HANDLE_NIL) err = (params.result == SHFL_FILE_EXISTS) ? -EEXIST : -ENOENT; - if (err) { - kfree(sf_handle); + if (err) return err; - } - - /* the host may have given us different attr then requested */ - sf_i->force_restat = 1; - /* init our handle struct and add it to the inode's handles list */ - sf_handle->handle = params.handle; - sf_handle->root = VBOXSF_SBI(inode->i_sb)->root; - sf_handle->access_flags = access_flags; - kref_init(&sf_handle->refcount); - - mutex_lock(&sf_i->handle_list_mutex); - list_add(&sf_handle->head, &sf_i->handle_list); - mutex_unlock(&sf_i->handle_list_mutex); + sf_handle = vboxsf_create_sf_handle(inode, params.handle, access_flags); + if (IS_ERR(sf_handle)) { + vboxsf_close(sbi->root, params.handle); + return PTR_ERR(sf_handle); + } file->private_data = sf_handle; return 0; @@ -114,22 +127,26 @@ static void vboxsf_handle_release(struct kref *refcount) kfree(sf_handle); } -static int vboxsf_file_release(struct inode *inode, struct file *file) +void vboxsf_release_sf_handle(struct inode *inode, struct vboxsf_handle *sf_handle) { struct vboxsf_inode *sf_i = VBOXSF_I(inode); - struct vboxsf_handle *sf_handle = file->private_data; + mutex_lock(&sf_i->handle_list_mutex); + list_del(&sf_handle->head); + mutex_unlock(&sf_i->handle_list_mutex); + + kref_put(&sf_handle->refcount, vboxsf_handle_release); +} + +static int vboxsf_file_release(struct inode *inode, struct file *file) +{ /* * When a file is closed on our (the guest) side, we want any subsequent * accesses done on the host side to see all changes done from our side. */ filemap_write_and_wait(inode->i_mapping); - mutex_lock(&sf_i->handle_list_mutex); - list_del(&sf_handle->head); - mutex_unlock(&sf_i->handle_list_mutex); - - kref_put(&sf_handle->refcount, vboxsf_handle_release); + vboxsf_release_sf_handle(inode, file->private_data); return 0; } diff --git a/fs/vboxsf/vfsmod.h b/fs/vboxsf/vfsmod.h index 6a7a9cedebc6e..9047befa66c5a 100644 --- a/fs/vboxsf/vfsmod.h +++ b/fs/vboxsf/vfsmod.h @@ -18,6 +18,8 @@ #define VBOXSF_SBI(sb) ((struct vboxsf_sbi *)(sb)->s_fs_info) #define VBOXSF_I(i) container_of(i, struct vboxsf_inode, vfs_inode) +struct vboxsf_handle; + struct vboxsf_options { unsigned long ttl; kuid_t uid; @@ -80,6 +82,11 @@ extern const struct file_operations vboxsf_reg_fops; extern const struct address_space_operations vboxsf_reg_aops; extern const struct dentry_operations vboxsf_dentry_ops; +/* from file.c */ +struct vboxsf_handle *vboxsf_create_sf_handle(struct inode *inode, + u64 handle, u32 access_flags); +void vboxsf_release_sf_handle(struct inode *inode, struct vboxsf_handle *sf_handle); + /* from utils.c */ struct inode *vboxsf_new_inode(struct super_block *sb); int vboxsf_init_inode(struct vboxsf_sbi *sbi, struct inode *inode, From 52dfd86aa568e433b24357bb5fc725560f1e22d8 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Thu, 21 Jan 2021 12:54:18 +0100 Subject: [PATCH 4/4] vboxsf: Add support for the atomic_open directory-inode op Opening a new file is done in 2 steps on regular filesystems: 1. Call the create inode-op on the parent-dir to create an inode to hold the meta-data related to the file. 2. Call the open file-op to get a handle for the file. vboxsf however does not really use disk-backed inodes because it is based on passing through file-related system-calls through to the hypervisor. So both steps translate to an open(2) call being passed through to the hypervisor. With the handle returned by the first call immediately being closed again. Making 2 open calls for a single open(..., O_CREATE, ...) calls has 2 problems: a) It is not really efficient. b) It actually breaks some apps. An example of b) is doing a git clone inside a vboxsf mount. When git clone tries to create a tempfile to store the pak files which is downloading the following happens: 1. vboxsf_dir_mkfile() gets called with a mode of 0444 and succeeds. 2. vboxsf_file_open() gets called with file->f_flags containing O_RDWR. When the host is a Linux machine this fails because doing a open(..., O_RDWR) on a file which exists and has mode 0444 results in an -EPERM error. Other network-filesystems and fuse avoid the problem of needing to pass 2 open() calls to the other side by using the atomic_open directory-inode op. This commit fixes git clone not working inside a vboxsf mount, by adding support for the atomic_open directory-inode op. As an added bonus this should also make opening new files faster. The atomic_open implementation is modelled after the atomic_open implementations from the 9p and fuse code. Fixes: 0fd169576648 ("fs: Add VirtualBox guest shared folder (vboxsf) support") Reported-by: Ludovic Pouzenc Signed-off-by: Hans de Goede --- fs/vboxsf/dir.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/fs/vboxsf/dir.c b/fs/vboxsf/dir.c index 87d5b2fef592b..c4769a9396c50 100644 --- a/fs/vboxsf/dir.c +++ b/fs/vboxsf/dir.c @@ -308,6 +308,53 @@ static int vboxsf_dir_mkdir(struct user_namespace *mnt_userns, return vboxsf_dir_create(parent, dentry, mode, true, true, NULL); } +static int vboxsf_dir_atomic_open(struct inode *parent, struct dentry *dentry, + struct file *file, unsigned int flags, umode_t mode) +{ + struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb); + struct vboxsf_handle *sf_handle; + struct dentry *res = NULL; + u64 handle; + int err; + + if (d_in_lookup(dentry)) { + res = vboxsf_dir_lookup(parent, dentry, 0); + if (IS_ERR(res)) + return PTR_ERR(res); + + if (res) + dentry = res; + } + + /* Only creates */ + if (!(flags & O_CREAT) || d_really_is_positive(dentry)) + return finish_no_open(file, res); + + err = vboxsf_dir_create(parent, dentry, mode, false, flags & O_EXCL, &handle); + if (err) + goto out; + + sf_handle = vboxsf_create_sf_handle(d_inode(dentry), handle, SHFL_CF_ACCESS_READWRITE); + if (IS_ERR(sf_handle)) { + vboxsf_close(sbi->root, handle); + err = PTR_ERR(sf_handle); + goto out; + } + + err = finish_open(file, dentry, generic_file_open); + if (err) { + /* This also closes the handle passed to vboxsf_create_sf_handle() */ + vboxsf_release_sf_handle(d_inode(dentry), sf_handle); + goto out; + } + + file->private_data = sf_handle; + file->f_mode |= FMODE_CREATED; +out: + dput(res); + return err; +} + static int vboxsf_dir_unlink(struct inode *parent, struct dentry *dentry) { struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb); @@ -428,6 +475,7 @@ const struct inode_operations vboxsf_dir_iops = { .lookup = vboxsf_dir_lookup, .create = vboxsf_dir_mkfile, .mkdir = vboxsf_dir_mkdir, + .atomic_open = vboxsf_dir_atomic_open, .rmdir = vboxsf_dir_unlink, .unlink = vboxsf_dir_unlink, .rename = vboxsf_dir_rename,