f2fs: handle error cases of memory donation

In cases of removing memory donation, we need to handle some error cases
like ENOENT and EACCES (indicating the range already has been donated).

Signed-off-by: Daeho Jeong <[e-mail]>
Reviewed-by: Chao Yu <[e-mail]>
Signed-off-by: Jaegeuk Kim <[e-mail]>

fs/f2fs/f2fs.h

···
 	FI_ATOMIC_DIRTIED,	/* indicate atomic file is dirtied */
 	FI_ATOMIC_REPLACE,	/* indicate atomic replace */
 	FI_OPENED_FILE,		/* indicate file has been opened */
+	FI_DONATE_FINISHED,	/* indicate page donation of file has been finished */
 	FI_MAX,			/* max flag, never be used */
 };
 

fs/f2fs/file.c

···
 	return ret;
 }
 
-static void f2fs_keep_noreuse_range(struct inode *inode,
+static int f2fs_keep_noreuse_range(struct inode *inode,
 				loff_t offset, loff_t len)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	u64 max_bytes = F2FS_BLK_TO_BYTES(max_file_blocks(inode));
 	u64 start, end;
+	int ret = 0;
 
 	if (!S_ISREG(inode->i_mode))
-		return;
+		return 0;
 
 	if (offset >= max_bytes || len > max_bytes ||
 	    (offset + len) > max_bytes)
-		return;
+		return 0;
 
 	start = offset >> PAGE_SHIFT;
 	end = DIV_ROUND_UP(offset + len, PAGE_SIZE);
···
 	inode_lock(inode);
 	if (f2fs_is_atomic_file(inode)) {
 		inode_unlock(inode);
-		return;
+		return 0;
 	}
 
 	spin_lock(&sbi->inode_lock[DONATE_INODE]);
···
 		if (!list_empty(&F2FS_I(inode)->gdonate_list)) {
 			list_del_init(&F2FS_I(inode)->gdonate_list);
 			sbi->donate_files--;
-		}
+			if (is_inode_flag_set(inode, FI_DONATE_FINISHED))
+				ret = -EALREADY;
+			else
+				set_inode_flag(inode, FI_DONATE_FINISHED);
+		} else
+			ret = -ENOENT;
 	} else {
 		if (list_empty(&F2FS_I(inode)->gdonate_list)) {
 			list_add_tail(&F2FS_I(inode)->gdonate_list,
···
 		}
 		F2FS_I(inode)->donate_start = start;
 		F2FS_I(inode)->donate_end = end - 1;
+		clear_inode_flag(inode, FI_DONATE_FINISHED);
 	}
 	spin_unlock(&sbi->inode_lock[DONATE_INODE]);
 	inode_unlock(inode);
+
+	return ret;
 }
 
 static int f2fs_ioc_fitrim(struct file *filp, unsigned long arg)
···
 	     f2fs_compressed_file(inode)))
 		f2fs_invalidate_compress_pages(F2FS_I_SB(inode), inode->i_ino);
 	else if (advice == POSIX_FADV_NOREUSE)
-		f2fs_keep_noreuse_range(inode, offset, len);
-	return 0;
+		err = f2fs_keep_noreuse_range(inode, offset, len);
+	return err;
 }
 
 #ifdef CONFIG_COMPAT

fs/f2fs/shrinker.c

···
 		if (!inode)
 			continue;
 
-		len = fi->donate_end - fi->donate_start + 1;
-		npages = npages < len ? 0 : npages - len;
-		invalidate_inode_pages2_range(inode->i_mapping,
+		inode_lock(inode);
+		if (!is_inode_flag_set(inode, FI_DONATE_FINISHED)) {
+			len = fi->donate_end - fi->donate_start + 1;
+			npages = npages < len ? 0 : npages - len;
+
+			invalidate_inode_pages2_range(inode->i_mapping,
 					fi->donate_start, fi->donate_end);
+			set_inode_flag(inode, FI_DONATE_FINISHED);
+		}
+		inode_unlock(inode);
+
 		iput(inode);
 		cond_resched();
 	}