fs/reiserfs/inode: remove dead code in _get_block_create_0()

Since commit 27b3a5c5 ("kill-the-bkl/reiserfs: drop the fs race
watchdog from _get_block_create_0()"), which removed a label that may
have the pointer 'p' touched in its control flow, related if statements
now eval to constant value now. Just remove them.

Assigning value NULL to p here
293     char *p = NULL;

In the following conditional expression, the value of p is always NULL,
As a result, the kunmap() cannot be executed.
308	if (p)
309		kunmap(bh_result->b_page);

355	if (p)
356		kunmap(bh_result->b_page);

366	if (p)
367		kunmap(bh_result->b_page);

Also, the kmap() cannot be executed.
399	if (!p)
400		p = (char *)kmap(bh_result->b_page);

[JK: Removed unnecessary initialization of 'p' to NULL]
Signed-off-by: Zeng Jingxiang <linuszeng@tencent.com>
Signed-off-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220720083029.1065578-1-zengjx95@gmail.com

fs/reiserfs/inode.c

@@ -290,7 +290,7 @@ static int _get_block_create_0(struct inode *inode, sector_t block,
 	struct buffer_head *bh;
 	struct item_head *ih, tmp_ih;
 	b_blocknr_t blocknr;
-	char *p = NULL;
+	char *p;
 	int chars;
 	int ret;
 	int result;
@@ -305,8 +305,6 @@ static int _get_block_create_0(struct inode *inode, sector_t block,
 	result = search_for_position_by_key(inode->i_sb, &key, &path);
 	if (result != POSITION_FOUND) {
 		pathrelse(&path);
-		if (p)
-			kunmap(bh_result->b_page);
 		if (result == IO_ERROR)
 			return -EIO;
 		/*
@@ -352,8 +350,6 @@ static int _get_block_create_0(struct inode *inode, sector_t block,
 		}
 
 		pathrelse(&path);
-		if (p)
-			kunmap(bh_result->b_page);
 		return ret;
 	}
 	/* requested data are in direct item(s) */
@@ -363,8 +359,6 @@ static int _get_block_create_0(struct inode *inode, sector_t block,
 		 * when it is stored in direct item(s)
 		 */
 		pathrelse(&path);
-		if (p)
-			kunmap(bh_result->b_page);
 		return -ENOENT;
 	}
 
@@ -396,9 +390,7 @@ static int _get_block_create_0(struct inode *inode, sector_t block,
 	 * sure we need to.  But, this means the item might move if
 	 * kmap schedules
 	 */
-	if (!p)
 	p = (char *)kmap(bh_result->b_page);
-
 	p += offset;
 	memset(p, 0, inode->i_sb->s_blocksize);
 	do {