Just wondering if we should add an fsync_range syscall like AIX and
some BSDs have? It's pretty simple for the pagecache since it
already implements the full sync with range syncs anyway. For
filesystems and user programs, I imagine it is a bit easier to
convert to fsync_range from fsync rather than use the sync_file_range
syscall.
Having a flags argument is nice, but AIX seems to use O_SYNC as a
flag, I wonder if we should follow?
Patch isn't complete...
---
fs/sync.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 50 insertions(+), 4 deletions(-)
Index: linux-2.6/fs/sync.c
===================================================================
--- linux-2.6.orig/fs/sync.c
+++ linux-2.6/fs/sync.c
@@ -76,10 +76,12 @@ int file_fsync(struct file *filp, struct
}
/**
- * vfs_fsync - perform a fsync or fdatasync on a file
+ * vfs_fsync_range - perform a fsync or fdatasync on part of a file
* @file: file to sync
* @dentry: dentry of @file
* @data: only perform a fdatasync operation
+ * @start: first byte to be synced
+ * @end: last byte to be synced
*
* Write back data and metadata for @file to disk. If @datasync is
* set only metadata needed to access modified file data is written.
@@ -88,7 +90,8 @@ int file_fsync(struct file *filp, struct
* only @dentry is set. This can only happen when the filesystem
* implements the export_operations API.
*/
-int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
+int vfs_fsync_range(struct file *file, struct dentry *dentry, int datasync,
+ loff_t start, loff_t end)
{
const struct file_operations *fop;
struct address_space *mapping;
@@ -112,7 +115,7 @@ int vfs_fsync(struct file *file, struct
goto out;
}
- ret = filemap_fdatawrite(mapping);
+ ret = filemap_fdatawrite_range(mapping, start, end);
/*
* We need to protect against concurrent writers, which could cause
@@ -123,12 +126,32 @@ int vfs_fsync(struct file *file, struct
if (!ret)
ret = err;
mutex_unlock(&mapping->host->i_mutex);
- err = filemap_fdatawait(mapping);
+ err = wait_on_page_writeback_range(mapping,
+ start >> PAGE_CACHE_SHIFT, end >> PAGE_CACHE_SHIFT);
if (!ret)
ret = err;
out:
return ret;
}
+EXPORT_SYMBOL(vfs_fsync_range);
+
+/**
+ * vfs_fsync - perform a fsync or fdatasync on a file
+ * @file: file to sync
+ * @dentry: dentry of @file
+ * @data: only perform a fdatasync operation
+ *
+ * Write back data and metadata for @file to disk. If @datasync is
+ * set only metadata needed to access modified file data is written.
+ *
+ * In case this function is called from nfsd @file may be %NULL and
+ * only @dentry is set. This can only happen when the filesystem
+ * implements the export_operations API.
+ */
+int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
+{
+ return vfs_fsync_range(file, dentry, datasync, 0, LLONG_MAX);
+}
EXPORT_SYMBOL(vfs_fsync);
static int do_fsync(unsigned int fd, int datasync)
@@ -154,6 +177,29 @@ SYSCALL_DEFINE1(fdatasync, unsigned int,
return do_fsync(fd, 1);
}
+SYSCALL_DEFINE(fsync_range)(int fd, int how, loff_t start, loff_t length)
+{
+ struct file *file;
+ loff_t end;
+ int ret = -EBADF;
+
+ if (how != O_DSYNC && how != O_SYNC)
+ return -EINVAL;
+
+ if (length == 0)
+ end = LLONG_MAX;
+ else
+ end = start + length - 1;
+
+ file = fget(fd);
+ if (file) {
+ ret = vfs_fsync_range(file, file->f_path.dentry, how == O_DSYNC,
+ start, end);
+ fput(file);
+ }
+ return ret;
+}
+
/*
* sys_sync_file_range() permits finely controlled syncing over a segment of
* a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
