udf: reduce stack usage of udf_load_pvoldesc

Allocate strings with kmalloc.

Checkstack output:
Before: udf_process_sequence:      712
After:  udf_process_sequence:      200

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 6275582..8364b17 100644 (file)
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -902,14 +902,23 @@ static int udf_find_fileset(struct super_block *sb,
 static int udf_load_pvoldesc(struct super_block *sb, sector_t block)
 {
        struct primaryVolDesc *pvoldesc;
-       struct ustr instr;
-       struct ustr outstr;
+       struct ustr *instr, *outstr;
        struct buffer_head *bh;
        uint16_t ident;
+       int ret = 1;
+
+       instr = kmalloc(sizeof(struct ustr), GFP_NOFS);
+       if (!instr)
+               return 1;
+
+       outstr = kmalloc(sizeof(struct ustr), GFP_NOFS);
+       if (!outstr)
+               goto out1;
 
        bh = udf_read_tagged(sb, block, block, &ident);
        if (!bh)
-               return 1;
+               goto out2;
+
        BUG_ON(ident != TAG_IDENT_PVD);
 
        pvoldesc = (struct primaryVolDesc *)bh->b_data;
@@ -925,20 +934,25 @@ static int udf_load_pvoldesc(struct super_block *sb, sector_t block)
 #endif
        }
 
-       if (!udf_build_ustr(&instr, pvoldesc->volIdent, 32))
-               if (udf_CS0toUTF8(&outstr, &instr)) {
-                       strncpy(UDF_SB(sb)->s_volume_ident, outstr.u_name,
-                               outstr.u_len > 31 ? 31 : outstr.u_len);
+       if (!udf_build_ustr(instr, pvoldesc->volIdent, 32))
+               if (udf_CS0toUTF8(outstr, instr)) {
+                       strncpy(UDF_SB(sb)->s_volume_ident, outstr->u_name,
+                               outstr->u_len > 31 ? 31 : outstr->u_len);
                        udf_debug("volIdent[] = '%s'\n",
                                        UDF_SB(sb)->s_volume_ident);
                }
 
-       if (!udf_build_ustr(&instr, pvoldesc->volSetIdent, 128))
-               if (udf_CS0toUTF8(&outstr, &instr))
-                       udf_debug("volSetIdent[] = '%s'\n", outstr.u_name);
+       if (!udf_build_ustr(instr, pvoldesc->volSetIdent, 128))
+               if (udf_CS0toUTF8(outstr, instr))
+                       udf_debug("volSetIdent[] = '%s'\n", outstr->u_name);
 
        brelse(bh);
-       return 0;
+       ret = 0;
+out2:
+       kfree(outstr);
+out1:
+       kfree(instr);
+       return ret;
 }
 
 static int udf_load_metadata_files(struct super_block *sb, int partition)