fs: ext2: Fix nbytes_to_read calculation in ext2_inode_read()

Fix incorrect nbytes_to_read calculation in ext2_inode_read() function.
Previously nbytes_to_read was decremented by read value which caused
incorrect calculation of bytes to read in subsequent iterations.
Now nbytes_to_read is decremented by to_read value which represents
the actual number of bytes read in current iteration.

This fixes potential data corruption issues when reading files from
ext2 filesystem.

Signed-off-by: Chen Shu <[email protected]>
(cherry picked from commit 5a5f05b)

Author: CsBoBoNice

subsys/fs/ext2/ext2_impl.c

@@ -630,7 +630,7 @@ ssize_t ext2_inode_read(struct ext2_inode *inode, void *buf, uint32_t offset, si
 		memcpy((uint8_t *)buf + read, inode_current_block_mem(inode) + block_off, to_read);
 
 		read += to_read;
-		nbytes_to_read -= read;
+		nbytes_to_read -= to_read;
 		offset += to_read;
 	}