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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-27 17:07:12 +0100 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-27 17:07:12 +0100 |
commit | 5ceabb6078b80a8544ba86d6ee523ad755ae6d5e (patch) | |
tree | 69ebf199a0fb3caece18596ad11f75354a96b654 /fs/namespace.c | |
parent | Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/g... (diff) | |
parent | whack-a-mole: don't open-code iminor/imajor (diff) | |
download | linux-5ceabb6078b80a8544ba86d6ee523ad755ae6d5e.tar.xz linux-5ceabb6078b80a8544ba86d6ee523ad755ae6d5e.zip |
Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull misc vfs updates from Al Viro:
"Assorted stuff pile - no common topic here"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
whack-a-mole: don't open-code iminor/imajor
9p: fix misuse of sscanf() in v9fs_stat2inode()
audit_alloc_mark(): don't open-code ERR_CAST()
fs/inode.c: make inode_init_always() initialize i_ino to 0
vfs: don't unnecessarily clone write access for writable fds
Diffstat (limited to 'fs/namespace.c')
-rw-r--r-- | fs/namespace.c | 53 |
1 files changed, 20 insertions, 33 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 062fe984a697..56bb5a5fdc0d 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -381,50 +381,36 @@ int mnt_want_write(struct vfsmount *m) EXPORT_SYMBOL_GPL(mnt_want_write); /** - * mnt_clone_write - get write access to a mount - * @mnt: the mount on which to take a write - * - * This is effectively like mnt_want_write, except - * it must only be used to take an extra write reference - * on a mountpoint that we already know has a write reference - * on it. This allows some optimisation. - * - * After finished, mnt_drop_write must be called as usual to - * drop the reference. - */ -int mnt_clone_write(struct vfsmount *mnt) -{ - /* superblock may be r/o */ - if (__mnt_is_readonly(mnt)) - return -EROFS; - preempt_disable(); - mnt_inc_writers(real_mount(mnt)); - preempt_enable(); - return 0; -} -EXPORT_SYMBOL_GPL(mnt_clone_write); - -/** * __mnt_want_write_file - get write access to a file's mount * @file: the file who's mount on which to take a write * - * This is like __mnt_want_write, but it takes a file and can - * do some optimisations if the file is open for write already + * This is like __mnt_want_write, but if the file is already open for writing it + * skips incrementing mnt_writers (since the open file already has a reference) + * and instead only does the check for emergency r/o remounts. This must be + * paired with __mnt_drop_write_file. */ int __mnt_want_write_file(struct file *file) { - if (!(file->f_mode & FMODE_WRITER)) - return __mnt_want_write(file->f_path.mnt); - else - return mnt_clone_write(file->f_path.mnt); + if (file->f_mode & FMODE_WRITER) { + /* + * Superblock may have become readonly while there are still + * writable fd's, e.g. due to a fs error with errors=remount-ro + */ + if (__mnt_is_readonly(file->f_path.mnt)) + return -EROFS; + return 0; + } + return __mnt_want_write(file->f_path.mnt); } /** * mnt_want_write_file - get write access to a file's mount * @file: the file who's mount on which to take a write * - * This is like mnt_want_write, but it takes a file and can - * do some optimisations if the file is open for write already + * This is like mnt_want_write, but if the file is already open for writing it + * skips incrementing mnt_writers (since the open file already has a reference) + * and instead only does the freeze protection and the check for emergency r/o + * remounts. This must be paired with mnt_drop_write_file. */ int mnt_want_write_file(struct file *file) { @@ -470,7 +456,8 @@ EXPORT_SYMBOL_GPL(mnt_drop_write); void __mnt_drop_write_file(struct file *file) { - __mnt_drop_write(file->f_path.mnt); + if (!(file->f_mode & FMODE_WRITER)) + __mnt_drop_write(file->f_path.mnt); } void mnt_drop_write_file(struct file *file) |