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authorFabian Frederick <fabf@skynet.be>2014-06-04 16:06:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-04 16:53:55 -0700
commitac13a829f6adb674015ab399594c089990104af7 (patch)
tree29f0b78758080bac01307e705371283a406b41c4
parentfd2916bd77109b69891573fd1e1205ecc619893e (diff)
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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." [akpm@linux-foundation.org: nuke ifdef] [akpm@linux-foundation.org: fix warning] Signed-off-by: Fabian Frederick <fabf@skynet.be> Suggested-by: Jan Kara <jack@suse.cz> Suggested-by: Christoph Hellwig <hch@infradead.org> Cc: Jan Kara <jack@suse.cz> Cc: Christoph Hellwig <hch@infradead.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/libfs.c34
-rw-r--r--include/linux/blkdev.h9
-rw-r--r--include/linux/fs.h1
3 files changed, 41 insertions, 3 deletions
diff --git a/fs/libfs.c b/fs/libfs.c
index a1844244246f..88e3e00e2eca 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -3,6 +3,7 @@
* Library for filesystems writers.
*/
+#include <linux/blkdev.h>
#include <linux/export.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
@@ -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;
@@ -952,10 +956,34 @@ 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;
+ return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
+}
EXPORT_SYMBOL(generic_file_fsync);
/**
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 8aba35f46f87..45cf6e537c83 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1607,6 +1607,9 @@ struct block_device_operations {
extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
unsigned long);
#else /* CONFIG_BLOCK */
+
+struct block_device;
+
/*
* stubs for when the block layer is configured out
*/
@@ -1642,6 +1645,12 @@ static inline bool blk_needs_flush_plug(struct task_struct *tsk)
return false;
}
+static inline int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
+ sector_t *error_sector)
+{
+ return 0;
+}
+
#endif /* CONFIG_BLOCK */
#endif
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);