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Subject[PATCH 1/2] 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>
Cc: Jan Kara <jack@suse.cz>
---
fs/udf/super.c | 36 +++++++++++++++++++++++++-----------
1 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index e25e701..dfe0277 100644
--- 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)
--
1.5.6.4


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