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From:   "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To:     Evgeniy Dushistov <dushistov@mail.ru>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Ira Weiny <ira.weiny@intel.com>, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Subject: [PATCH v2] fs/ufs: Replace kmap() with kmap_local_page()
Date:   Mon,  9 May 2022 09:12:07 +0200
Message-Id: <20220509071207.16176-1-fmdefrancesco@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The use of kmap() is being deprecated in favor of kmap_local_page(). With
kmap_local_page(), the mapping is thread-local, CPU-local and not globally
visible.

The usage of kmap_local_page() in fs/ufs is thread-local, therefore replace
kmap() / kunmap() calls with kmap_local_page() / kunmap_local().

kunmap_local() requires the mapping address, so return that address from
ufs_get_page() to be used in ufs_put_page().

These changes are essentially ported from fs/ext2 and relie largely on
commit 782b76d7abdf ("fs/ext2: Replace kmap() with kmap_local_page()").

Suggested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---

v1 -> v2: Correct some style's issues reported by checkpatch.pl.
	  Remove "inline" compiler directive from fs/ufs/ufs.h,
	  Reported-by: kernel test robot <lkp@intel.com>

 fs/ufs/dir.c   | 116 +++++++++++++++++++++++++++++++------------------
 fs/ufs/namei.c |  38 ++++++++--------
 fs/ufs/ufs.h   |  12 +++--
 3 files changed, 102 insertions(+), 64 deletions(-)

diff --git a/fs/ufs/dir.c b/fs/ufs/dir.c
index b721d0bda5e5..39e81547ebb9 100644
--- a/fs/ufs/dir.c
+++ b/fs/ufs/dir.c
@@ -61,9 +61,9 @@ static int ufs_commit_chunk(struct page *page, loff_t pos, unsigned len)
 	return err;
 }
 
-static inline void ufs_put_page(struct page *page)
+inline void ufs_put_page(struct page *page, void *page_addr)
 {
-	kunmap(page);
+	kunmap_local(page_addr);
 	put_page(page);
 }
 
@@ -72,11 +72,12 @@ ino_t ufs_inode_by_name(struct inode *dir, const struct qstr *qstr)
 	ino_t res = 0;
 	struct ufs_dir_entry *de;
 	struct page *page;
-	
-	de = ufs_find_entry(dir, qstr, &page);
+	void *page_addr;
+
+	de = ufs_find_entry(dir, qstr, &page, &page_addr);
 	if (de) {
 		res = fs32_to_cpu(dir->i_sb, de->d_ino);
-		ufs_put_page(page);
+		ufs_put_page(page, page_addr);
 	}
 	return res;
 }
@@ -84,11 +85,11 @@ ino_t ufs_inode_by_name(struct inode *dir, const struct qstr *qstr)
 
 /* Releases the page */
 void ufs_set_link(struct inode *dir, struct ufs_dir_entry *de,
-		  struct page *page, struct inode *inode,
-		  bool update_times)
+		  struct page *page, void *page_addr,
+		  struct inode *inode, bool update_times)
 {
 	loff_t pos = page_offset(page) +
-			(char *) de - (char *) page_address(page);
+			(char *)de - (char *)page_addr;
 	unsigned len = fs16_to_cpu(dir->i_sb, de->d_reclen);
 	int err;
 
@@ -100,18 +101,17 @@ void ufs_set_link(struct inode *dir, struct ufs_dir_entry *de,
 	ufs_set_de_type(dir->i_sb, de, inode->i_mode);
 
 	err = ufs_commit_chunk(page, pos, len);
-	ufs_put_page(page);
+	ufs_put_page(page, page_addr);
 	if (update_times)
 		dir->i_mtime = dir->i_ctime = current_time(dir);
 	mark_inode_dirty(dir);
 }
 
 
-static bool ufs_check_page(struct page *page)
+static bool ufs_check_page(struct page *page, char *kaddr)
 {
 	struct inode *dir = page->mapping->host;
 	struct super_block *sb = dir->i_sb;
-	char *kaddr = page_address(page);
 	unsigned offs, rec_len;
 	unsigned limit = PAGE_SIZE;
 	const unsigned chunk_mask = UFS_SB(sb)->s_uspi->s_dirblksize - 1;
@@ -186,21 +186,28 @@ static bool ufs_check_page(struct page *page)
 	return false;
 }
 
-static struct page *ufs_get_page(struct inode *dir, unsigned long n)
+/*
+ * Calls to ufs_get_page()/ufs_put_page() must be nested according to the
+ * rules documented in kmap_local_page()/kunmap_local().
+ *
+ * NOTE: ufs_find_entry() and ufs_dotdot() act as calls to ufs_get_page()
+ * and must be treated accordingly for nesting purposes.
+ */
+static struct page *ufs_get_page(struct inode *dir, unsigned long n, void **page_addr)
 {
 	struct address_space *mapping = dir->i_mapping;
 	struct page *page = read_mapping_page(mapping, n, NULL);
 	if (!IS_ERR(page)) {
-		kmap(page);
+		*page_addr = kmap_local_page(page);
 		if (unlikely(!PageChecked(page))) {
-			if (PageError(page) || !ufs_check_page(page))
+			if (PageError(page) || !ufs_check_page(page, *page_addr))
 				goto fail;
 		}
 	}
 	return page;
 
 fail:
-	ufs_put_page(page);
+	ufs_put_page(page, *page_addr);
 	return ERR_PTR(-EIO);
 }
 
@@ -226,15 +233,29 @@ ufs_next_entry(struct super_block *sb, struct ufs_dir_entry *p)
 					fs16_to_cpu(sb, p->d_reclen));
 }
 
-struct ufs_dir_entry *ufs_dotdot(struct inode *dir, struct page **p)
+/*
+ * Return the '..' directory entry and the page in which the entry was found
+ * (as a parameter - p).
+ *
+ * On Success ufs_put_page() should be called on *p.
+ *
+ * NOTE: Calls to ufs_get_page()/ufs_put_page() must be nested according to
+ * the rules documented in kmap_local_page()/kunmap_local().
+ *
+ * ufs_find_entry() and ufs_dotdot() act as calls to ufs_get_page() and
+ * must be treated accordingly for nesting purposes.
+ */
+struct ufs_dir_entry *ufs_dotdot(struct inode *dir, struct page **p, void **pa)
 {
-	struct page *page = ufs_get_page(dir, 0);
+	void *page_addr;
+	struct page *page = ufs_get_page(dir, 0, &page_addr);
 	struct ufs_dir_entry *de = NULL;
 
 	if (!IS_ERR(page)) {
 		de = ufs_next_entry(dir->i_sb,
-				    (struct ufs_dir_entry *)page_address(page));
+				    (struct ufs_dir_entry *)page_addr);
 		*p = page;
+		*pa = page_addr;
 	}
 	return de;
 }
@@ -246,9 +267,17 @@ struct ufs_dir_entry *ufs_dotdot(struct inode *dir, struct page **p)
  * returns the page in which the entry was found, and the entry itself
  * (as a parameter - res_dir). Page is returned mapped and unlocked.
  * Entry is guaranteed to be valid.
+ *
+ * On Success ufs_put_page() should be called on *res_page.
+ *
+ * NOTE: Calls to ufs_get_page()/ufs_put_page() must be nested according to
+ * the rules documented in kmap_local_page()/kunmap_local().
+ *
+ * ufs_find_entry() and ufs_dotdot() act as calls to ufs_get_page() and
+ * must be treated accordingly for nesting purposes.
  */
 struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
-				     struct page **res_page)
+				     struct page **res_page, void **res_page_addr)
 {
 	struct super_block *sb = dir->i_sb;
 	const unsigned char *name = qstr->name;
@@ -259,6 +288,7 @@ struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
 	struct page *page = NULL;
 	struct ufs_inode_info *ui = UFS_I(dir);
 	struct ufs_dir_entry *de;
+	void *page_addr;
 
 	UFSD("ENTER, dir_ino %lu, name %s, namlen %u\n", dir->i_ino, name, namelen);
 
@@ -267,6 +297,7 @@ struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
 
 	/* OFFSET_CACHE */
 	*res_page = NULL;
+	*res_page_addr = NULL;
 
 	start = ui->i_dir_start_lookup;
 
@@ -275,9 +306,10 @@ struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
 	n = start;
 	do {
 		char *kaddr;
-		page = ufs_get_page(dir, n);
+
+		page = ufs_get_page(dir, n, &page_addr);
 		if (!IS_ERR(page)) {
-			kaddr = page_address(page);
+			kaddr = page_addr;
 			de = (struct ufs_dir_entry *) kaddr;
 			kaddr += ufs_last_byte(dir, n) - reclen;
 			while ((char *) de <= kaddr) {
@@ -285,7 +317,7 @@ struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
 					goto found;
 				de = ufs_next_entry(sb, de);
 			}
-			ufs_put_page(page);
+			ufs_put_page(page, page_addr);
 		}
 		if (++n >= npages)
 			n = 0;
@@ -295,6 +327,7 @@ struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
 
 found:
 	*res_page = page;
+	*res_page_addr = page_addr;
 	ui->i_dir_start_lookup = n;
 	return de;
 }
@@ -312,6 +345,7 @@ int ufs_add_link(struct dentry *dentry, struct inode *inode)
 	const unsigned int chunk_size = UFS_SB(sb)->s_uspi->s_dirblksize;
 	unsigned short rec_len, name_len;
 	struct page *page = NULL;
+	void *page_addr = NULL;
 	struct ufs_dir_entry *de;
 	unsigned long npages = dir_pages(dir);
 	unsigned long n;
@@ -329,12 +363,12 @@ int ufs_add_link(struct dentry *dentry, struct inode *inode)
 	for (n = 0; n <= npages; n++) {
 		char *dir_end;
 
-		page = ufs_get_page(dir, n);
+		page = ufs_get_page(dir, n, &page_addr);
 		err = PTR_ERR(page);
 		if (IS_ERR(page))
 			goto out;
 		lock_page(page);
-		kaddr = page_address(page);
+		kaddr = page_addr;
 		dir_end = kaddr + ufs_last_byte(dir, n);
 		de = (struct ufs_dir_entry *)kaddr;
 		kaddr += PAGE_SIZE - reclen;
@@ -365,14 +399,14 @@ int ufs_add_link(struct dentry *dentry, struct inode *inode)
 			de = (struct ufs_dir_entry *) ((char *) de + rec_len);
 		}
 		unlock_page(page);
-		ufs_put_page(page);
+		ufs_put_page(page, page_addr);
 	}
 	BUG();
 	return -EINVAL;
 
 got_it:
 	pos = page_offset(page) +
-			(char*)de - (char*)page_address(page);
+			(char *)de - (char *)page_addr;
 	err = ufs_prepare_chunk(page, pos, rec_len);
 	if (err)
 		goto out_unlock;
@@ -396,7 +430,7 @@ int ufs_add_link(struct dentry *dentry, struct inode *inode)
 	mark_inode_dirty(dir);
 	/* OFFSET_CACHE */
 out_put:
-	ufs_put_page(page);
+	ufs_put_page(page, page_addr);
 out:
 	return err;
 out_unlock:
@@ -441,7 +475,7 @@ ufs_readdir(struct file *file, struct dir_context *ctx)
 		char *kaddr, *limit;
 		struct ufs_dir_entry *de;
 
-		struct page *page = ufs_get_page(inode, n);
+		struct page *page = ufs_get_page(inode, n, (void **)&kaddr);
 
 		if (IS_ERR(page)) {
 			ufs_error(sb, __func__,
@@ -450,7 +484,6 @@ ufs_readdir(struct file *file, struct dir_context *ctx)
 			ctx->pos += PAGE_SIZE - offset;
 			return -EIO;
 		}
-		kaddr = page_address(page);
 		if (unlikely(need_revalidate)) {
 			if (offset) {
 				offset = ufs_validate_entry(sb, kaddr, offset, chunk_mask);
@@ -476,13 +509,13 @@ ufs_readdir(struct file *file, struct dir_context *ctx)
 					       ufs_get_de_namlen(sb, de),
 					       fs32_to_cpu(sb, de->d_ino),
 					       d_type)) {
-					ufs_put_page(page);
+					ufs_put_page(page, kaddr);
 					return 0;
 				}
 			}
 			ctx->pos += fs16_to_cpu(sb, de->d_reclen);
 		}
-		ufs_put_page(page);
+		ufs_put_page(page, kaddr);
 	}
 	return 0;
 }
@@ -493,10 +526,9 @@ ufs_readdir(struct file *file, struct dir_context *ctx)
  * previous entry.
  */
 int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
-		     struct page * page)
+		     struct page *page, char *kaddr)
 {
 	struct super_block *sb = inode->i_sb;
-	char *kaddr = page_address(page);
 	unsigned from = ((char*)dir - kaddr) & ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
 	unsigned to = ((char*)dir - kaddr) + fs16_to_cpu(sb, dir->d_reclen);
 	loff_t pos;
@@ -522,7 +554,7 @@ int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
 		de = ufs_next_entry(sb, de);
 	}
 	if (pde)
-		from = (char*)pde - (char*)page_address(page);
+		from = (char *)pde - kaddr;
 
 	pos = page_offset(page) + from;
 	lock_page(page);
@@ -535,7 +567,7 @@ int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
 	inode->i_ctime = inode->i_mtime = current_time(inode);
 	mark_inode_dirty(inode);
 out:
-	ufs_put_page(page);
+	ufs_put_page(page, kaddr);
 	UFSD("EXIT\n");
 	return err;
 }
@@ -559,8 +591,7 @@ int ufs_make_empty(struct inode * inode, struct inode *dir)
 		goto fail;
 	}
 
-	kmap(page);
-	base = (char*)page_address(page);
+	base = kmap_local_page(page);
 	memset(base, 0, PAGE_SIZE);
 
 	de = (struct ufs_dir_entry *) base;
@@ -577,7 +608,7 @@ int ufs_make_empty(struct inode * inode, struct inode *dir)
 	de->d_reclen = cpu_to_fs16(sb, chunk_size - UFS_DIR_REC_LEN(1));
 	ufs_set_de_namlen(sb, de, 2);
 	strcpy (de->d_name, "..");
-	kunmap(page);
+	kunmap_local(base);
 
 	err = ufs_commit_chunk(page, 0, chunk_size);
 fail:
@@ -592,17 +623,18 @@ int ufs_empty_dir(struct inode * inode)
 {
 	struct super_block *sb = inode->i_sb;
 	struct page *page = NULL;
+	void *page_addr;
 	unsigned long i, npages = dir_pages(inode);
 
 	for (i = 0; i < npages; i++) {
 		char *kaddr;
 		struct ufs_dir_entry *de;
-		page = ufs_get_page(inode, i);
 
+		page = ufs_get_page(inode, i, &page_addr);
 		if (IS_ERR(page))
 			continue;
 
-		kaddr = page_address(page);
+		kaddr = page_addr;
 		de = (struct ufs_dir_entry *)kaddr;
 		kaddr += ufs_last_byte(inode, i) - UFS_DIR_REC_LEN(1);
 
@@ -629,12 +661,12 @@ int ufs_empty_dir(struct inode * inode)
 			}
 			de = ufs_next_entry(sb, de);
 		}
-		ufs_put_page(page);
+		ufs_put_page(page, page_addr);
 	}
 	return 1;
 
 not_empty:
-	ufs_put_page(page);
+	ufs_put_page(page, page_addr);
 	return 0;
 }
 
diff --git a/fs/ufs/namei.c b/fs/ufs/namei.c
index 29d5a0e0c8f0..bc7060d10dd2 100644
--- a/fs/ufs/namei.c
+++ b/fs/ufs/namei.c
@@ -210,13 +210,14 @@ static int ufs_unlink(struct inode *dir, struct dentry *dentry)
 	struct inode * inode = d_inode(dentry);
 	struct ufs_dir_entry *de;
 	struct page *page;
+	void *page_addr;
 	int err = -ENOENT;
 
-	de = ufs_find_entry(dir, &dentry->d_name, &page);
+	de = ufs_find_entry(dir, &dentry->d_name, &page, &page_addr);
 	if (!de)
 		goto out;
 
-	err = ufs_delete_entry(dir, de, page);
+	err = ufs_delete_entry(dir, de, page, page_addr);
 	if (err)
 		goto out;
 
@@ -250,27 +251,31 @@ static int ufs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 	struct inode *old_inode = d_inode(old_dentry);
 	struct inode *new_inode = d_inode(new_dentry);
 	struct page *dir_page = NULL;
+	void *dir_page_addr;
 	struct ufs_dir_entry * dir_de = NULL;
 	struct page *old_page;
+	void *old_page_addr;
 	struct ufs_dir_entry *old_de;
 	int err = -ENOENT;
 
 	if (flags & ~RENAME_NOREPLACE)
 		return -EINVAL;
 
-	old_de = ufs_find_entry(old_dir, &old_dentry->d_name, &old_page);
+	old_de = ufs_find_entry(old_dir, &old_dentry->d_name, &old_page,
+				&old_page_addr);
 	if (!old_de)
 		goto out;
 
 	if (S_ISDIR(old_inode->i_mode)) {
 		err = -EIO;
-		dir_de = ufs_dotdot(old_inode, &dir_page);
+		dir_de = ufs_dotdot(old_inode, &dir_page, &dir_page_addr);
 		if (!dir_de)
 			goto out_old;
 	}
 
 	if (new_inode) {
 		struct page *new_page;
+		void *page_addr;
 		struct ufs_dir_entry *new_de;
 
 		err = -ENOTEMPTY;
@@ -278,10 +283,11 @@ static int ufs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 			goto out_dir;
 
 		err = -ENOENT;
-		new_de = ufs_find_entry(new_dir, &new_dentry->d_name, &new_page);
+		new_de = ufs_find_entry(new_dir, &new_dentry->d_name, &new_page,
+					&page_addr);
 		if (!new_de)
 			goto out_dir;
-		ufs_set_link(new_dir, new_de, new_page, old_inode, 1);
+		ufs_set_link(new_dir, new_de, new_page, page_addr, old_inode, 1);
 		new_inode->i_ctime = current_time(new_inode);
 		if (dir_de)
 			drop_nlink(new_inode);
@@ -300,29 +306,25 @@ static int ufs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 	 */
 	old_inode->i_ctime = current_time(old_inode);
 
-	ufs_delete_entry(old_dir, old_de, old_page);
+	ufs_delete_entry(old_dir, old_de, old_page, old_page_addr);
 	mark_inode_dirty(old_inode);
 
 	if (dir_de) {
 		if (old_dir != new_dir)
-			ufs_set_link(old_inode, dir_de, dir_page, new_dir, 0);
-		else {
-			kunmap(dir_page);
-			put_page(dir_page);
-		}
+			ufs_set_link(old_inode, dir_de, dir_page,
+				     dir_page_addr, new_dir, 0);
+		else
+			ufs_put_page(dir_page, dir_page_addr);
 		inode_dec_link_count(old_dir);
 	}
 	return 0;
 
 
 out_dir:
-	if (dir_de) {
-		kunmap(dir_page);
-		put_page(dir_page);
-	}
+	if (dir_de)
+		ufs_put_page(dir_page, dir_page_addr);
 out_old:
-	kunmap(old_page);
-	put_page(old_page);
+	ufs_put_page(old_page, old_page_addr);
 out:
 	return err;
 }
diff --git a/fs/ufs/ufs.h b/fs/ufs/ufs.h
index 550f7c5a3636..20d224c163ab 100644
--- a/fs/ufs/ufs.h
+++ b/fs/ufs/ufs.h
@@ -102,12 +102,16 @@ extern const struct inode_operations ufs_dir_inode_operations;
 extern int ufs_add_link (struct dentry *, struct inode *);
 extern ino_t ufs_inode_by_name(struct inode *, const struct qstr *);
 extern int ufs_make_empty(struct inode *, struct inode *);
-extern struct ufs_dir_entry *ufs_find_entry(struct inode *, const struct qstr *, struct page **);
-extern int ufs_delete_entry(struct inode *, struct ufs_dir_entry *, struct page *);
+extern struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
+					    struct page **res_page, void **res_page_addr);
+extern int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
+			    struct page *page, char *kaddr);
 extern int ufs_empty_dir (struct inode *);
-extern struct ufs_dir_entry *ufs_dotdot(struct inode *, struct page **);
+extern struct ufs_dir_entry *ufs_dotdot(struct inode *dir, struct page **p, void **pa);
 extern void ufs_set_link(struct inode *dir, struct ufs_dir_entry *de,
-			 struct page *page, struct inode *inode, bool update_times);
+			 struct page *page, void *page_addr,
+			 struct inode *inode, bool update_times);
+extern void ufs_put_page(struct page *page, void *page_addr);
 
 /* file.c */
 extern const struct inode_operations ufs_file_inode_operations;
-- 
2.34.1