[PATCH v3 4/5] vfs: freeze protect overlay inode on file_start_write()
From: Amir Goldstein <amir73il@gmail.com>
Date: 2017-01-31 08:35:28
Also in:
linux-fsdevel
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
Before writing to overlay file, need to check if either overlay or upper fs are frozen. This allows freezing overlayfs mount independently of freezing underlying fs. Signed-off-by: Amir Goldstein <amir73il@gmail.com> --- include/linux/fs.h | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 78c81e6..8a4dbc6 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h@@ -2534,14 +2534,26 @@ static inline void file_start_write(struct file *file) { if (!S_ISREG(file_inode(file)->i_mode)) return; + __sb_start_write(locks_inode(file)->i_sb, SB_FREEZE_WRITE, true); + if (likely(locks_inode(file) == file_inode(file))) + return; __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true); + } static inline bool file_start_write_trylock(struct file *file) { + int ret; + if (!S_ISREG(file_inode(file)->i_mode)) return true; - return __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, false); + ret = __sb_start_write(locks_inode(file)->i_sb, SB_FREEZE_WRITE, false); + if (!ret || likely(locks_inode(file) == file_inode(file))) + return ret; + ret = __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, false); + if (!ret) + __sb_end_write(locks_inode(file)->i_sb, SB_FREEZE_WRITE); + return ret; } static inline void file_end_write(struct file *file)
@@ -2549,6 +2561,9 @@ static inline void file_end_write(struct file *file) if (!S_ISREG(file_inode(file)->i_mode)) return; __sb_end_write(file_inode(file)->i_sb, SB_FREEZE_WRITE); + if (likely(locks_inode(file) == file_inode(file))) + return; + __sb_end_write(locks_inode(file)->i_sb, SB_FREEZE_WRITE); } static inline int do_clone_file_range(struct file *file_in, loff_t pos_in,
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2.7.4