Merge tag 'erofs-for-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs

Pull erofs updates from Gao Xiang:
 "Still no new features for this cycle, as some ongoing improvements
  remain premature for now.

  This includes a micro-optimization for the superblock checksum, along
  with minor bugfixes and code cleanups, as usual:

   - Micro-optimize superblock checksum

   - Avoid overly large bvecs[] for file-backed mounts

   - Some leftover folio conversion in z_erofs_bind_cache()

   - Minor bugfixes and cleanups"

* tag 'erofs-for-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: refine z_erofs_get_extent_compressedlen()
  erofs: remove dead code in erofs_fc_parse_param
  erofs: return SHRINK_EMPTY if no objects to free
  erofs: convert z_erofs_bind_cache() to folios
  erofs: tidy up zdata.c
  erofs: get rid of `z_erofs_next_pcluster_t`
  erofs: simplify z_erofs_load_compact_lcluster()
  erofs: fix potential return value overflow of z_erofs_shrink_scan()
  erofs: shorten bvecs[] for file-backed mounts
  erofs: micro-optimize superblock checksum
  fs: erofs: xattr.c change kzalloc to kcalloc

Author: torvalds

fs/erofs/compress.h

@@ -29,29 +29,8 @@ struct z_erofs_decompressor {
 	char *name;
 };
 
-/* some special page->private (unsigned long, see below) */
 #define Z_EROFS_SHORTLIVED_PAGE		(-1UL << 2)
-#define Z_EROFS_PREALLOCATED_PAGE	(-2UL << 2)
-
-/*
- * For all pages in a pcluster, page->private should be one of
- * Type                         Last 2bits      page->private
- * short-lived page             00              Z_EROFS_SHORTLIVED_PAGE
- * preallocated page (tryalloc) 00              Z_EROFS_PREALLOCATED_PAGE
- * cached/managed page          00              pointer to z_erofs_pcluster
- * online page (file-backed,    01/10/11        sub-index << 2 | count
- *              some pages can be used for inplace I/O)
- *
- * page->mapping should be one of
- * Type                 page->mapping
- * short-lived page     NULL
- * preallocated page    NULL
- * cached/managed page  non-NULL or NULL (invalidated/truncated page)
- * online page          non-NULL
- *
- * For all managed pages, PG_private should be set with 1 extra refcount,
- * which is used for page reclaim / migration.
- */
+#define Z_EROFS_PREALLOCATED_FOLIO	((void *)(-2UL << 2))
 
 /*
  * Currently, short-lived pages are pages directly from buddy system

fs/erofs/erofs_fs.h

@@ -9,6 +9,7 @@
 #ifndef __EROFS_FS_H
 #define __EROFS_FS_H
 
+/* to allow for x86 boot sectors and other oddities. */
 #define EROFS_SUPER_OFFSET      1024
 
 #define EROFS_FEATURE_COMPAT_SB_CHKSUM          0x00000001
@@ -54,7 +55,7 @@ struct erofs_deviceslot {
 /* erofs on-disk super block (currently 128 bytes) */
 struct erofs_super_block {
 	__le32 magic;           /* file system magic number */
-	__le32 checksum;        /* crc32c(super_block) */
+	__le32 checksum;        /* crc32c to avoid unexpected on-disk overlap */
 	__le32 feature_compat;
 	__u8 blkszbits;         /* filesystem block size in bit shift */
 	__u8 sb_extslots;	/* superblock size = 128 + sb_extslots * 16 */

fs/erofs/fileio.c

@@ -6,7 +6,7 @@
 #include <trace/events/erofs.h>
 
 struct erofs_fileio_rq {
-	struct bio_vec bvecs[BIO_MAX_VECS];
+	struct bio_vec bvecs[16];
 	struct bio bio;
 	struct kiocb iocb;
 	struct super_block *sb;
@@ -68,7 +68,7 @@ static struct erofs_fileio_rq *erofs_fileio_rq_alloc(struct erofs_map_dev *mdev)
 	struct erofs_fileio_rq *rq = kzalloc(sizeof(*rq),
 					     GFP_KERNEL | __GFP_NOFAIL);
 
-	bio_init(&rq->bio, NULL, rq->bvecs, BIO_MAX_VECS, REQ_OP_READ);
+	bio_init(&rq->bio, NULL, rq->bvecs, ARRAY_SIZE(rq->bvecs), REQ_OP_READ);
 	rq->iocb.ki_filp = mdev->m_dif->file;
 	rq->sb = mdev->m_sb;
 	return rq;

fs/erofs/super.c

@@ -39,29 +39,21 @@ void _erofs_printk(struct super_block *sb, const char *fmt, ...)
 
 static int erofs_superblock_csum_verify(struct super_block *sb, void *sbdata)
 {
-	size_t len = 1 << EROFS_SB(sb)->blkszbits;
-	struct erofs_super_block *dsb;
-	u32 expected_crc, crc;
+	struct erofs_super_block *dsb = sbdata + EROFS_SUPER_OFFSET;
+	u32 len = 1 << EROFS_SB(sb)->blkszbits, crc;
 
 	if (len > EROFS_SUPER_OFFSET)
 		len -= EROFS_SUPER_OFFSET;
+	len -= offsetof(struct erofs_super_block, checksum) +
+			sizeof(dsb->checksum);
 
-	dsb = kmemdup(sbdata + EROFS_SUPER_OFFSET, len, GFP_KERNEL);
-	if (!dsb)
-		return -ENOMEM;
-
-	expected_crc = le32_to_cpu(dsb->checksum);
-	dsb->checksum = 0;
-	/* to allow for x86 boot sectors and other oddities. */
-	crc = crc32c(~0, dsb, len);
-	kfree(dsb);
-
-	if (crc != expected_crc) {
-		erofs_err(sb, "invalid checksum 0x%08x, 0x%08x expected",
-			  crc, expected_crc);
-		return -EBADMSG;
-	}
-	return 0;
+	/* skip .magic(pre-verified) and .checksum(0) fields */
+	crc = crc32c(0x5045B54A, (&dsb->checksum) + 1, len);
+	if (crc == le32_to_cpu(dsb->checksum))
+		return 0;
+	erofs_err(sb, "invalid checksum 0x%08x, 0x%08x expected",
+		  crc, le32_to_cpu(dsb->checksum));
+	return -EBADMSG;
 }
 
 static void erofs_inode_init_once(void *ptr)
@@ -516,8 +508,6 @@ static int erofs_fc_parse_param(struct fs_context *fc,
 		errorfc(fc, "%s option not supported", erofs_fs_parameters[opt].name);
 #endif
 		break;
-	default:
-		return -ENOPARAM;
 	}
 	return 0;
 }

fs/erofs/xattr.c

@@ -478,7 +478,7 @@ int erofs_xattr_prefixes_init(struct super_block *sb)
 	if (!sbi->xattr_prefix_count)
 		return 0;
 
-	pfs = kzalloc(sbi->xattr_prefix_count * sizeof(*pfs), GFP_KERNEL);
+	pfs = kcalloc(sbi->xattr_prefix_count, sizeof(*pfs), GFP_KERNEL);
 	if (!pfs)
 		return -ENOMEM;