vfs: atomic f_pos accesses as per POSIX

[~andy/linux] / include / linux / fs.h

diff --git a/include/linux/fs.h b/include/linux/fs.h
index d79678c188ad5a1831283b8a5051b30c5aa03ee4..ebfde04bca0683f1e2ecd2aa5c273b943eb7dfb9 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -123,6 +123,9 @@ typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 /* File is opened with O_PATH; almost nothing can be done with it */
 #define FMODE_PATH             ((__force fmode_t)0x4000)
 
+/* File needs atomic accesses to f_pos */
+#define FMODE_ATOMIC_POS       ((__force fmode_t)0x8000)
+
 /* File was opened by fanotify and shouldn't generate fanotify events */
 #define FMODE_NONOTIFY         ((__force fmode_t)0x1000000)
 
@@ -780,13 +783,14 @@ struct file {
        const struct file_operations    *f_op;
 
        /*
-        * Protects f_ep_links, f_flags, f_pos vs i_size in lseek SEEK_CUR.
+        * Protects f_ep_links, f_flags.
         * Must not be taken from IRQ context.
         */
        spinlock_t              f_lock;
        atomic_long_t           f_count;
        unsigned int            f_flags;
        fmode_t                 f_mode;
+       struct mutex            f_pos_lock;
        loff_t                  f_pos;
        struct fown_struct      f_owner;
        const struct cred       *f_cred;
@@ -2274,7 +2278,13 @@ extern int filemap_fdatawrite_range(struct address_space *mapping,
 extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
                           int datasync);
 extern int vfs_fsync(struct file *file, int datasync);
-extern int generic_write_sync(struct file *file, loff_t pos, loff_t count);
+static inline int generic_write_sync(struct file *file, loff_t pos, loff_t count)
+{
+       if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
+               return 0;
+       return vfs_fsync_range(file, pos, pos + count - 1,
+                              (file->f_flags & __O_SYNC) ? 0 : 1);
+}
 extern void emergency_sync(void);
 extern void emergency_remount(void);
 #ifdef CONFIG_BLOCK