[PATCH] Minix: add the necessary check in case IO error happens

[shilong wang <wangshilong1991@xxxxxxxxx>]

I am a newbie trying to study about filesystem, when i am reviewing
code with minix filesystem, i think the function 'alloc_branch' in the
file 'itree_common.c' lack the necessary check about IO ERROR.

As we know 'sb_getblk' may fail,but it dosen't do necessary check
with it.

Signed-off-by: Wang shilong <wangshilong1991@xxxxxxxxx>
---
 fs/minix/itree_common.c |   23 +++++++++++++++++------
 1 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/fs/minix/itree_common.c b/fs/minix/itree_common.c
index a731cab..e5a61f8 100644
--- a/fs/minix/itree_common.c
+++ b/fs/minix/itree_common.c
@@ -73,17 +73,28 @@ static int alloc_branch(struct inode *inode,
 {
 	int n = 0;
 	int i;
+	int err = 0;
 	int parent = minix_new_block(inode);
+	if (!parent) {
+		err = -ENOSPC;
+		goto failed;
+	}

 	branch[0].key = cpu_to_block(parent);
-	if (parent) for (n = 1; n < num; n++) {
+	for (n = 1; n < num; n++) {
 		struct buffer_head *bh;
 		/* Allocate the next block */
 		int nr = minix_new_block(inode);
-		if (!nr)
-			break;
+		if (!nr) {
+			err = -ENOSPC;
+			goto failed;
+		}
 		branch[n].key = cpu_to_block(nr);
 		bh = sb_getblk(inode->i_sb, parent);
+		if (!bh) {
+			err = -EIO;
+			goto failed;
+		}
 		lock_buffer(bh);
 		memset(bh->b_data, 0, bh->b_size);
 		branch[n].bh = bh;
@@ -95,14 +106,14 @@ static int alloc_branch(struct inode *inode,
 		parent = nr;
 	}
 	if (n == num)
-		return 0;
-
+		return err;
+failed:
 	/* Allocation failed, free what we already allocated */
 	for (i = 1; i < n; i++)
 		bforget(branch[i].bh);
 	for (i = 0; i < n; i++)
 		minix_free_block(inode, block_to_cpu(branch[i].key));
-	return -ENOSPC;
+	return err;
 }

 static inline int splice_branch(struct inode *inode,
-- 
1.7.7.6
--
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