fs: handle FIEMAP_FLAG_SYNC in fiemap_prep

By moving FIEMAP_FLAG_SYNC handling to fiemap_prep we ensure it is
handled once instead of duplicated, but can still be done under fs locks,
like xfs/iomap intended with its duplicate handling.  Also make sure the
error value of filemap_write_and_wait is propagated to user space.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Link: https://lore.kernel.org/r/20200523073016.2944131-8-hch@lst.de
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/btrfs/inode.c

@@ -8243,14 +8243,12 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 	return ret;
 }
 
-#define BTRFS_FIEMAP_FLAGS	(FIEMAP_FLAG_SYNC)
-
 static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		__u64 start, __u64 len)
 {
 	int	ret;
 
-	ret = fiemap_prep(inode, fieinfo, start, &len, BTRFS_FIEMAP_FLAGS);
+	ret = fiemap_prep(inode, fieinfo, start, &len, 0);
 	if (ret)
 		return ret;
 

fs/cifs/smb2ops.c

@@ -3408,8 +3408,7 @@ static int smb3_fiemap(struct cifs_tcon *tcon,
 	int i, num, rc, flags, last_blob;
 	u64 next;
 
-	rc = fiemap_prep(d_inode(cfile->dentry), fei, start, &len,
+	rc = fiemap_prep(d_inode(cfile->dentry), fei, start, &len, 0);
-			FIEMAP_FLAG_SYNC);
 	if (rc)
 		return rc;
 

fs/ext4/extents.c

@@ -4938,7 +4938,7 @@ int ext4_get_es_cache(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		fieinfo->fi_flags &= ~FIEMAP_FLAG_CACHE;
 	}
 
-	error = fiemap_prep(inode, fieinfo, start, &len, FIEMAP_FLAG_SYNC);
+	error = fiemap_prep(inode, fieinfo, start, &len, 0);
 	if (error)
 		return error;
 

fs/ext4/ioctl.c

@@ -759,9 +759,6 @@ static int ext4_ioctl_get_es_cache(struct file *filp, unsigned long arg)
 		       fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
 		return -EFAULT;
 
-	if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
-		filemap_write_and_wait(inode->i_mapping);
-
 	error = ext4_get_es_cache(inode, &fieinfo, fiemap.fm_start,
 			fiemap.fm_length);
 	fiemap.fm_flags = fieinfo.fi_flags;

fs/f2fs/data.c

@@ -1825,8 +1825,7 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			return ret;
 	}
 
-	ret = fiemap_prep(inode, fieinfo, start, &len,
+	ret = fiemap_prep(inode, fieinfo, start, &len, FIEMAP_FLAG_XATTR);
-			FIEMAP_FLAG_SYNC | FIEMAP_FLAG_XATTR);
 	if (ret)
 		return ret;
 

fs/ioctl.c

@@ -166,6 +166,7 @@ int fiemap_prep(struct inode *inode, struct fiemap_extent_info *fieinfo,
 {
 	u64 maxbytes = inode->i_sb->s_maxbytes;
 	u32 incompat_flags;
+	int ret = 0;
 
 	if (*len == 0)
 		return -EINVAL;
@@ -178,13 +179,17 @@ int fiemap_prep(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	if (*len > maxbytes || (maxbytes - *len) < start)
 		*len = maxbytes - start;
 
+	supported_flags |= FIEMAP_FLAG_SYNC;
 	supported_flags &= FIEMAP_FLAGS_COMPAT;
 	incompat_flags = fieinfo->fi_flags & ~supported_flags;
 	if (incompat_flags) {
 		fieinfo->fi_flags = incompat_flags;
 		return -EBADR;
 	}
-	return 0;
+
+	if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC)
+		ret = filemap_write_and_wait(inode->i_mapping);
+	return ret;
 }
 EXPORT_SYMBOL(fiemap_prep);
 
@@ -213,9 +218,6 @@ static int ioctl_fiemap(struct file *filp, struct fiemap __user *ufiemap)
 		       fieinfo.fi_extents_max * sizeof(struct fiemap_extent)))
 		return -EFAULT;
 
-	if (fieinfo.fi_flags & FIEMAP_FLAG_SYNC)
-		filemap_write_and_wait(inode->i_mapping);
-
 	error = inode->i_op->fiemap(inode, &fieinfo, fiemap.fm_start,
 			fiemap.fm_length);
 	fiemap.fm_flags = fieinfo.fi_flags;

fs/iomap/fiemap.c

@@ -75,16 +75,10 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
 	ctx.fi = fi;
 	ctx.prev.type = IOMAP_HOLE;
 
-	ret = fiemap_prep(inode, fi, start, &len, FIEMAP_FLAG_SYNC);
+	ret = fiemap_prep(inode, fi, start, &len, 0);
 	if (ret)
 		return ret;
 
-	if (fi->fi_flags & FIEMAP_FLAG_SYNC) {
-		ret = filemap_write_and_wait(inode->i_mapping);
-		if (ret)
-			return ret;
-	}
-
 	while (len > 0) {
 		ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx,
 				iomap_fiemap_actor);

fs/nilfs2/inode.c

@@ -1006,7 +1006,7 @@ int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	unsigned int blkbits = inode->i_blkbits;
 	int ret, n;
 
-	ret = fiemap_prep(inode, fieinfo, start, &len, FIEMAP_FLAG_SYNC);
+	ret = fiemap_prep(inode, fieinfo, start, &len, 0);
 	if (ret)
 		return ret;
 

fs/ocfs2/extent_map.c

@@ -733,8 +733,6 @@ static int ocfs2_fiemap_inline(struct inode *inode, struct buffer_head *di_bh,
 	return 0;
 }
 
-#define OCFS2_FIEMAP_FLAGS	(FIEMAP_FLAG_SYNC)
-
 int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		 u64 map_start, u64 map_len)
 {
@@ -746,8 +744,7 @@ int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	struct buffer_head *di_bh = NULL;
 	struct ocfs2_extent_rec rec;
 
-	ret = fiemap_prep(inode, fieinfo, map_start, &map_len,
+	ret = fiemap_prep(inode, fieinfo, map_start, &map_len, 0);
-			OCFS2_FIEMAP_FLAGS);
 	if (ret)
 		return ret;
 

fs/overlayfs/inode.c

@@ -462,10 +462,6 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		return -EOPNOTSUPP;
 
 	old_cred = ovl_override_creds(inode->i_sb);
-
-	if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC)
-		filemap_write_and_wait(realinode->i_mapping);
-
 	err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
 	revert_creds(old_cred);