Fix Symbolic link remove problem

    When we create symbolic link, in simplefs_new_inode function, the symbolic
does not use ei_block to record the using block. But in simplefs_unlink functoin
we use the ei_block to clean the bitmap, this makes the unlink will clean the "0"
bit in bitmap.

Close #58

Author: RoyWFHuang

inode.c

@@ -640,7 +640,6 @@ static int simplefs_unlink(struct inode *dir, struct dentry *dentry)
     inode->i_size = 0;
     i_uid_write(inode, 0);
     i_gid_write(inode, 0);
-    inode->i_mode = 0;
 
 #if SIMPLEFS_AT_LEAST(6, 7, 0)
     inode_set_mtime(inode, 0, 0);
@@ -658,7 +657,9 @@ static int simplefs_unlink(struct inode *dir, struct dentry *dentry)
     mark_inode_dirty(inode);
 
     /* Free inode and index block from bitmap */
-    put_blocks(sbi, bno, 1);
+    if (!S_ISLNK(inode->i_mode))
+        put_blocks(sbi, bno, 1);
+    inode->i_mode = 0;
     put_inode(sbi, ino);
 
     return ret;

script/test.sh

@@ -13,7 +13,7 @@ MAXFILES=40920        # max files per dir
 MOUNT_TEST=100
 
 test_op() {
-    local op=$1 
+    local op=$1
     echo
     echo -n "Testing cmd: $op..."
     sudo sh -c "$op" >/dev/null && echo "Success"
@@ -26,15 +26,15 @@ check_exist() {
     echo
     echo -n "Check if exist: $mode $nlink $name..."
     sudo ls -lR  | grep -e "$mode $nlink".*$name >/dev/null && echo "Success" || \
-    echo "Failed" 
+    echo "Failed"
 }
 
 if [ "$EUID" -eq 0 ]
   then echo "Don't run this script as root"
   exit
 fi
 
-mkdir -p test  
+mkdir -p test
 sudo umount test 2>/dev/null
 sleep 1
 sudo rmmod simplefs 2>/dev/null
@@ -123,12 +123,22 @@ test_op 'dd if=/dev/zero of=file bs=1M count=12 status=none'
 filesize=$(sudo ls -lR  | grep -e "$F_MOD 2".*file | awk '{print $5}')
 test $filesize -le $MAXFILESIZE || echo "Failed, file size over the limit"
 
+# test remove symbolic link
+test_op 'ln -s file symlink_fake'
+test_op 'rm -f symlink_fake'
+test_op 'touch symlink_fake'
+test_op 'ln file symlink_hard_fake'
+test_op 'rm -f symlink_hard_fake'
+test_op 'touch symlink_hard_fake'
+
 # test if exist
-check_exist $D_MOD 3 dir 
+check_exist $D_MOD 3 dir
 check_exist $F_MOD 2 file
 check_exist $F_MOD 2 hdlink
 check_exist $D_MOD 2 dir
-check_exist $S_MOD 1 symlink 
+check_exist $S_MOD 1 symlink
+check_exist $F_MOD 1 symlink_fake
+check_exist $F_MOD 1 symlink_hard_fake
 
 sleep 1
 popd >/dev/null