From d56e0ddb8fc35a7aa13ab8f21c499a34f45dda05 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 15 Jun 2023 14:22:25 +0300 Subject: fs: rename {vfs,kernel}_tmpfile_open() Overlayfs and cachefiles use vfs_open_tmpfile() to open a tmpfile without accounting for nr_files. Rename this helper to kernel_tmpfile_open() to better reflect this helper is used for kernel internal users. Signed-off-by: Amir Goldstein Reviewed-by: Christoph Hellwig Message-Id: <20230615112229.2143178-2-amir73il@gmail.com> Signed-off-by: Christian Brauner --- include/linux/fs.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/linux/fs.h b/include/linux/fs.h index 21a981680856..62237beeac2a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1672,9 +1672,10 @@ static inline int vfs_whiteout(struct mnt_idmap *idmap, WHITEOUT_DEV); } -struct file *vfs_tmpfile_open(struct mnt_idmap *idmap, - const struct path *parentpath, - umode_t mode, int open_flag, const struct cred *cred); +struct file *kernel_tmpfile_open(struct mnt_idmap *idmap, + const struct path *parentpath, + umode_t mode, int open_flag, + const struct cred *cred); int vfs_mkobj(struct dentry *, umode_t, int (*f)(struct dentry *, umode_t, void *), -- cgit v1.2.3 From cbb0b9d4bbcfa96e7872808a63be03202536f1bc Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 15 Jun 2023 14:22:26 +0300 Subject: fs: use a helper for opening kernel internal files cachefiles uses kernel_open_tmpfile() to open kernel internal tmpfile without accounting for nr_files. cachefiles uses open_with_fake_path() for the same reason without the need for a fake path. Fork open_with_fake_path() to kernel_file_open() which only does the noaccount part and use it in cachefiles. Signed-off-by: Amir Goldstein Reviewed-by: Christoph Hellwig Message-Id: <20230615112229.2143178-3-amir73il@gmail.com> Signed-off-by: Christian Brauner --- include/linux/fs.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/linux/fs.h b/include/linux/fs.h index 62237beeac2a..1f8486e773af 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1676,6 +1676,8 @@ struct file *kernel_tmpfile_open(struct mnt_idmap *idmap, const struct path *parentpath, umode_t mode, int open_flag, const struct cred *cred); +struct file *kernel_file_open(const struct path *path, int flags, + struct inode *inode, const struct cred *cred); int vfs_mkobj(struct dentry *, umode_t, int (*f)(struct dentry *, umode_t, void *), -- cgit v1.2.3 From 62d53c4a1dfe347bd87ede46ffad38c9a3870338 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 15 Jun 2023 14:22:28 +0300 Subject: fs: use backing_file container for internal files with "fake" f_path Overlayfs uses open_with_fake_path() to allocate internal kernel files, with a "fake" path - whose f_path is not on the same fs as f_inode. Allocate a container struct backing_file for those internal files, that is used to hold the "fake" ovl path along with the real path. backing_file_real_path() can be used to access the stored real path. Signed-off-by: Amir Goldstein Message-Id: <20230615112229.2143178-5-amir73il@gmail.com> Signed-off-by: Christian Brauner --- include/linux/fs.h | 33 ++++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/linux/fs.h b/include/linux/fs.h index 1f8486e773af..24e1be1c13ca 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -171,6 +171,9 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset, /* File supports non-exclusive O_DIRECT writes from multiple threads */ #define FMODE_DIO_PARALLEL_WRITE ((__force fmode_t)0x1000000) +/* File is embedded in backing_file object */ +#define FMODE_BACKING ((__force fmode_t)0x2000000) + /* File was opened by fanotify and shouldn't generate fanotify events */ #define FMODE_NONOTIFY ((__force fmode_t)0x4000000) @@ -2352,11 +2355,31 @@ static inline struct file *file_open_root_mnt(struct vfsmount *mnt, return file_open_root(&(struct path){.mnt = mnt, .dentry = mnt->mnt_root}, name, flags, mode); } -extern struct file * dentry_open(const struct path *, int, const struct cred *); -extern struct file *dentry_create(const struct path *path, int flags, - umode_t mode, const struct cred *cred); -extern struct file * open_with_fake_path(const struct path *, int, - struct inode*, const struct cred *); +struct file *dentry_open(const struct path *path, int flags, + const struct cred *creds); +struct file *dentry_create(const struct path *path, int flags, umode_t mode, + const struct cred *cred); +struct file *backing_file_open(const struct path *path, int flags, + const struct path *real_path, + const struct cred *cred); +struct path *backing_file_real_path(struct file *f); + +/* + * file_real_path - get the path corresponding to f_inode + * + * When opening a backing file for a stackable filesystem (e.g., + * overlayfs) f_path may be on the stackable filesystem and f_inode on + * the underlying filesystem. When the path associated with f_inode is + * needed, this helper should be used instead of accessing f_path + * directly. +*/ +static inline const struct path *file_real_path(struct file *f) +{ + if (unlikely(f->f_mode & FMODE_BACKING)) + return backing_file_real_path(f); + return &f->f_path; +} + static inline struct file *file_clone_open(struct file *file) { return dentry_open(&file->f_path, file->f_flags, file->f_cred); -- cgit v1.2.3 From bc2473c90fca55bf95b2ab6af1dacee26a4f92f6 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 15 Jun 2023 14:22:29 +0300 Subject: ovl: enable fsnotify events on underlying real files Overlayfs creates the real underlying files with fake f_path, whose f_inode is on the underlying fs and f_path on overlayfs. Those real files were open with FMODE_NONOTIFY, because fsnotify code was not prapared to handle fsnotify hooks on files with fake path correctly and fanotify would report unexpected event->fd with fake overlayfs path, when the underlying fs was being watched. Teach fsnotify to handle events on the real files, and do not set real files to FMODE_NONOTIFY to allow operations on real file (e.g. open, access, modify, close) to generate async and permission events. Because fsnotify does not have notifications on address space operations, we do not need to worry about ->vm_file not reporting events to a watched overlayfs when users are accessing a mapped overlayfs file. Acked-by: Jan Kara Signed-off-by: Amir Goldstein Message-Id: <20230615112229.2143178-6-amir73il@gmail.com> Signed-off-by: Christian Brauner --- include/linux/fsnotify.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h index bb8467cd11ae..ed48e4f1e755 100644 --- a/include/linux/fsnotify.h +++ b/include/linux/fsnotify.h @@ -91,11 +91,13 @@ static inline void fsnotify_dentry(struct dentry *dentry, __u32 mask) static inline int fsnotify_file(struct file *file, __u32 mask) { - const struct path *path = &file->f_path; + const struct path *path; if (file->f_mode & FMODE_NONOTIFY) return 0; + /* Overlayfs internal files have fake f_path */ + path = file_real_path(file); return fsnotify_parent(path->dentry, mask, path, FSNOTIFY_EVENT_PATH); } -- cgit v1.2.3