From 2f2e34441b7be4f49cc3a9ac3e45b11353a03356 Mon Sep 17 00:00:00 2001 From: Fabian Frederick Date: Thu, 22 May 2014 10:42:35 +1000 Subject: [PATCH] fs/libfs.c: add generic data flush to fsync Description by Jan Kara: "A lot of older filesystems don't properly flush volatile disk caches on fsync(2) which can lead to loss of fsynced data after power failure. This patch makes generic_file_fsync() issue proper cache flush to fix the problem. Sysadmin can use /sys/devices/.../cache_type to tell the system it should not send the cache flush." Signed-off-by: Fabian Frederick Suggested-by: Jan Kara Suggested-by: Christoph Hellwig Cc: Jan Kara Cc: Christoph Hellwig Cc: Alexander Viro Cc: "Theodore Ts'o" Signed-off-by: Andrew Morton --- fs/libfs.c | 39 ++++++++++++++++++++++++++++++++++++--- include/linux/fs.h | 1 + 2 files changed, 37 insertions(+), 3 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index a1844244246f..3a704e194d63 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -3,6 +3,7 @@ * Library for filesystems writers. */ +#include #include #include #include @@ -923,16 +924,19 @@ struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, EXPORT_SYMBOL_GPL(generic_fh_to_parent); /** - * generic_file_fsync - generic fsync implementation for simple filesystems + * __generic_file_fsync - generic fsync implementation for simple filesystems + * * @file: file to synchronize + * @start: start offset in bytes + * @end: end offset in bytes (inclusive) * @datasync: only synchronize essential metadata if true * * This is a generic implementation of the fsync method for simple * filesystems which track all non-inode metadata in the buffers list * hanging off the address_space structure. */ -int generic_file_fsync(struct file *file, loff_t start, loff_t end, - int datasync) +int __generic_file_fsync(struct file *file, loff_t start, loff_t end, + int datasync) { struct inode *inode = file->f_mapping->host; int err; @@ -952,9 +956,38 @@ int generic_file_fsync(struct file *file, loff_t start, loff_t end, err = sync_inode_metadata(inode, 1); if (ret == 0) ret = err; + out: mutex_unlock(&inode->i_mutex); return ret; +} +EXPORT_SYMBOL(__generic_file_fsync); + +/** + * generic_file_fsync - generic fsync implementation for simple filesystems + * with flush + * @file: file to synchronize + * @start: start offset in bytes + * @end: end offset in bytes (inclusive) + * @datasync: only synchronize essential metadata if true + * + */ + +int generic_file_fsync(struct file *file, loff_t start, loff_t end, + int datasync) +{ + struct inode *inode = file->f_mapping->host; + int err; + + err = __generic_file_fsync(file, start, end, datasync); + if (err) + return err; +#ifdef CONFIG_BLOCK + return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); +#else + return err; +#endif + } EXPORT_SYMBOL(generic_file_fsync); diff --git a/include/linux/fs.h b/include/linux/fs.h index 878031227c57..c3f46e499dd0 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2590,6 +2590,7 @@ extern ssize_t simple_read_from_buffer(void __user *to, size_t count, extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, const void __user *from, size_t count); +extern int __generic_file_fsync(struct file *, loff_t, loff_t, int); extern int generic_file_fsync(struct file *, loff_t, loff_t, int); extern int generic_check_addressable(unsigned, u64); -- 2.39.5