fs: Split off inode_needs_update_time and __file_update_time

This splits off the functions inode_needs_update_time() and
__file_update_time() from the function file_update_time().

This is required to support async buffered writes.
No intended functional changes in this patch.

Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20220623175157.1715274-10-shr@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/inode.c b/fs/inode.c
index a2e1837..ff726d9 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -2049,35 +2049,18 @@ int file_remove_privs(struct file *file)
 }
 EXPORT_SYMBOL(file_remove_privs);
 
-/**
- *     file_update_time        -       update mtime and ctime time
- *     @file: file accessed
- *
- *     Update the mtime and ctime members of an inode and mark the inode
- *     for writeback.  Note that this function is meant exclusively for
- *     usage in the file write path of filesystems, and filesystems may
- *     choose to explicitly ignore update via this function with the
- *     S_NOCMTIME inode flag, e.g. for network filesystem where these
- *     timestamps are handled by the server.  This can return an error for
- *     file systems who need to allocate space in order to update an inode.
- */
-
-int file_update_time(struct file *file)
+static int inode_needs_update_time(struct inode *inode, struct timespec64 *now)
 {
-       struct inode *inode = file_inode(file);
-       struct timespec64 now;
        int sync_it = 0;
-       int ret;
 
        /* First try to exhaust all avenues to not sync */
        if (IS_NOCMTIME(inode))
                return 0;
 
-       now = current_time(inode);
-       if (!timespec64_equal(&inode->i_mtime, &now))
+       if (!timespec64_equal(&inode->i_mtime, now))
                sync_it = S_MTIME;
 
-       if (!timespec64_equal(&inode->i_ctime, &now))
+       if (!timespec64_equal(&inode->i_ctime, now))
                sync_it |= S_CTIME;
 
        if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode))
@@ -2086,15 +2069,50 @@ int file_update_time(struct file *file)
        if (!sync_it)
                return 0;
 
-       /* Finally allowed to write? Takes lock. */
-       if (__mnt_want_write_file(file))
-               return 0;
+       return sync_it;
+}
+
+static int __file_update_time(struct file *file, struct timespec64 *now,
+                       int sync_mode)
+{
+       int ret = 0;
+       struct inode *inode = file_inode(file);
 
-       ret = inode_update_time(inode, &now, sync_it);
-       __mnt_drop_write_file(file);
+       /* try to update time settings */
+       if (!__mnt_want_write_file(file)) {
+               ret = inode_update_time(inode, now, sync_mode);
+               __mnt_drop_write_file(file);
+       }
 
        return ret;
 }
+
+/**
+ * file_update_time - update mtime and ctime time
+ * @file: file accessed
+ *
+ * Update the mtime and ctime members of an inode and mark the inode for
+ * writeback. Note that this function is meant exclusively for usage in
+ * the file write path of filesystems, and filesystems may choose to
+ * explicitly ignore updates via this function with the _NOCMTIME inode
+ * flag, e.g. for network filesystem where these imestamps are handled
+ * by the server. This can return an error for file systems who need to
+ * allocate space in order to update an inode.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int file_update_time(struct file *file)
+{
+       int ret;
+       struct inode *inode = file_inode(file);
+       struct timespec64 now = current_time(inode);
+
+       ret = inode_needs_update_time(inode, &now);
+       if (ret <= 0)
+               return ret;
+
+       return __file_update_time(file, &now, ret);
+}
 EXPORT_SYMBOL(file_update_time);
 
 /**
@@ -2111,6 +2129,8 @@ EXPORT_SYMBOL(file_update_time);
 int file_modified(struct file *file)
 {
        int ret;
+       struct inode *inode = file_inode(file);
+       struct timespec64 now = current_time(inode);
 
        /*
         * Clear the security bits if the process is not being run by root.
@@ -2123,7 +2143,11 @@ int file_modified(struct file *file)
        if (unlikely(file->f_mode & FMODE_NOCMTIME))
                return 0;
 
-       return file_update_time(file);
+       ret = inode_needs_update_time(inode, &now);
+       if (ret <= 0)
+               return ret;
+
+       return __file_update_time(file, &now, ret);
 }
 EXPORT_SYMBOL(file_modified);