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Message-Id: <20210329065402.3297092-3-ira.weiny@intel.com>
Date: Sun, 28 Mar 2021 23:54:02 -0700
From: ira.weiny@...el.com
To: Jan Kara <jack@...e.com>
Cc: Ira Weiny <ira.weiny@...el.com>, linux-ext4@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] fs/ext2: Replace kmap() with kmap_local_page()
From: Ira Weiny <ira.weiny@...el.com>
The k[un]map() calls in ext2_[get|put]_page() are localized to a single
thread. kmap_local_page() is more efficient.
Replace the kmap/kunmap calls with kmap_local_page()/kunmap_local().
kunmap_local() requires the mapping address so return that address from
ext2_get_page() to be used in ext2_put_page(). This works well because
many of the callers need the address anyway so it is not bad to return
it along with the page.
In addition, kmap_local_page()/kunmap_local() require strict nesting
rules to be followed.
Document the new nesting requirements of ext2_get_page() and
ext2_put_page() as well as the relationship between ext2_get_page(),
ext2_find_entry(), and ext2_dotdot().
Adjust one ext2_put_page() call site in ext2_rename() to ensure the new
nesting requirements are met.
Finally, adjust code style for checkpatch.
To: Jan Kara <jack@...e.com>
Signed-off-by: Ira Weiny <ira.weiny@...el.com>
---
fs/ext2/dir.c | 89 ++++++++++++++++++++++++++++++++-----------------
fs/ext2/ext2.h | 12 ++++---
fs/ext2/namei.c | 35 +++++++++++--------
3 files changed, 87 insertions(+), 49 deletions(-)
diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index f0b8311cdf5b..14292dba3a12 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -190,13 +190,20 @@ static bool ext2_check_page(struct page *page, int quiet)
return false;
}
+/*
+ * Calls to ext2_get_page()/ext2_put_page() must be nested according to the
+ * rules documented in kmap_local_page()/kunmap_local().
+ *
+ * NOTE: ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page()
+ * and should be treated as a call to ext2_get_page() for nesting purposes.
+ */
static struct page * ext2_get_page(struct inode *dir, unsigned long n,
- int quiet)
+ int quiet, 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) || !ext2_check_page(page, quiet))
goto fail;
@@ -205,7 +212,7 @@ static struct page * ext2_get_page(struct inode *dir, unsigned long n,
return page;
fail:
- ext2_put_page(page);
+ ext2_put_page(page, *page_addr);
return ERR_PTR(-EIO);
}
@@ -276,7 +283,7 @@ ext2_readdir(struct file *file, struct dir_context *ctx)
for ( ; n < npages; n++, offset = 0) {
char *kaddr, *limit;
ext2_dirent *de;
- struct page *page = ext2_get_page(inode, n, 0);
+ struct page *page = ext2_get_page(inode, n, 0, (void **)&kaddr);
if (IS_ERR(page)) {
ext2_error(sb, __func__,
@@ -285,7 +292,6 @@ ext2_readdir(struct file *file, struct dir_context *ctx)
ctx->pos += PAGE_SIZE - offset;
return PTR_ERR(page);
}
- kaddr = page_address(page);
if (unlikely(need_revalidate)) {
if (offset) {
offset = ext2_validate_entry(kaddr, offset, chunk_mask);
@@ -300,7 +306,7 @@ ext2_readdir(struct file *file, struct dir_context *ctx)
if (de->rec_len == 0) {
ext2_error(sb, __func__,
"zero-length directory entry");
- ext2_put_page(page);
+ ext2_put_page(page, kaddr);
return -EIO;
}
if (de->inode) {
@@ -312,13 +318,13 @@ ext2_readdir(struct file *file, struct dir_context *ctx)
if (!dir_emit(ctx, de->name, de->name_len,
le32_to_cpu(de->inode),
d_type)) {
- ext2_put_page(page);
+ ext2_put_page(page, kaddr);
return 0;
}
}
ctx->pos += ext2_rec_len_from_disk(de->rec_len);
}
- ext2_put_page(page);
+ ext2_put_page(page, kaddr);
}
return 0;
}
@@ -332,9 +338,16 @@ ext2_readdir(struct file *file, struct dir_context *ctx)
* Entry is guaranteed to be valid.
*
* On Success ext2_put_page() should be called on *res_page.
+ *
+ * NOTE: Calls to ext2_get_page()/ext2_put_page() must be nested according to
+ * the rules documented in kmap_local_page()/kunmap_local().
+ *
+ * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page() and
+ * should be treated as a call to ext2_get_page() for nesting purposes.
*/
struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
- const struct qstr *child, struct page **res_page)
+ const struct qstr *child, struct page **res_page,
+ void **res_page_addr)
{
const char *name = child->name;
int namelen = child->len;
@@ -344,12 +357,14 @@ struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
struct page *page = NULL;
struct ext2_inode_info *ei = EXT2_I(dir);
ext2_dirent * de;
+ void *page_addr;
if (npages == 0)
goto out;
/* OFFSET_CACHE */
*res_page = NULL;
+ *res_page_addr = NULL;
start = ei->i_dir_start_lookup;
if (start >= npages)
@@ -357,25 +372,25 @@ struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
n = start;
do {
char *kaddr;
- page = ext2_get_page(dir, n, 0);
+ page = ext2_get_page(dir, n, 0, &page_addr);
if (IS_ERR(page))
return ERR_CAST(page);
- kaddr = page_address(page);
+ kaddr = page_addr;
de = (ext2_dirent *) kaddr;
kaddr += ext2_last_byte(dir, n) - reclen;
while ((char *) de <= kaddr) {
if (de->rec_len == 0) {
ext2_error(dir->i_sb, __func__,
"zero-length directory entry");
- ext2_put_page(page);
+ ext2_put_page(page, page_addr);
goto out;
}
if (ext2_match(namelen, name, de))
goto found;
de = ext2_next_entry(de);
}
- ext2_put_page(page);
+ ext2_put_page(page, page_addr);
if (++n >= npages)
n = 0;
@@ -393,6 +408,7 @@ struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
found:
*res_page = page;
+ *res_page_addr = page_addr;
ei->i_dir_start_lookup = n;
return de;
}
@@ -402,15 +418,24 @@ struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
* (as a parameter - p).
*
* On Success ext2_put_page() should be called on *p.
+ *
+ * NOTE: Calls to ext2_get_page()/ext2_put_page() must be nested according to
+ * the rules documented in kmap_local_page()/kunmap_local().
+ *
+ * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_page() and
+ * should be treated as a call to ext2_get_page() for nesting purposes.
*/
-struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
+struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct page **p,
+ void **pa)
{
- struct page *page = ext2_get_page(dir, 0, 0);
+ void *page_addr;
+ struct page *page = ext2_get_page(dir, 0, 0, &page_addr);
ext2_dirent *de = NULL;
if (!IS_ERR(page)) {
- de = ext2_next_entry((ext2_dirent *) page_address(page));
+ de = ext2_next_entry((ext2_dirent *) page_addr);
*p = page;
+ *pa = page_addr;
}
return de;
}
@@ -419,13 +444,14 @@ int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino)
{
struct ext2_dir_entry_2 *de;
struct page *page;
+ void *page_addr;
- de = ext2_find_entry(dir, child, &page);
+ de = ext2_find_entry(dir, child, &page, &page_addr);
if (IS_ERR(de))
return PTR_ERR(de);
*ino = le32_to_cpu(de->inode);
- ext2_put_page(page);
+ ext2_put_page(page, page_addr);
return 0;
}
@@ -435,10 +461,11 @@ static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
}
void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
- struct page *page, struct inode *inode, int update_times)
+ struct page *page, void *page_addr, struct inode *inode,
+ int update_times)
{
loff_t pos = page_offset(page) +
- (char *) de - (char *) page_address(page);
+ (char *) de - (char *) page_addr;
unsigned len = ext2_rec_len_from_disk(de->rec_len);
int err;
@@ -466,10 +493,10 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
unsigned reclen = EXT2_DIR_REC_LEN(namelen);
unsigned short rec_len, name_len;
struct page *page = NULL;
+ void *page_addr = NULL;
ext2_dirent * de;
unsigned long npages = dir_pages(dir);
unsigned long n;
- char *kaddr;
loff_t pos;
int err;
@@ -479,14 +506,15 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
* to protect that region.
*/
for (n = 0; n <= npages; n++) {
+ char *kaddr;
char *dir_end;
- page = ext2_get_page(dir, n, 0);
+ page = ext2_get_page(dir, n, 0, &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 + ext2_last_byte(dir, n);
de = (ext2_dirent *)kaddr;
kaddr += PAGE_SIZE - reclen;
@@ -517,14 +545,14 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
de = (ext2_dirent *) ((char *) de + rec_len);
}
unlock_page(page);
- ext2_put_page(page);
+ ext2_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 = ext2_prepare_chunk(page, pos, rec_len);
if (err)
goto out_unlock;
@@ -544,7 +572,7 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
mark_inode_dirty(dir);
/* OFFSET_CACHE */
out_put:
- ext2_put_page(page);
+ ext2_put_page(page, page_addr);
out:
return err;
out_unlock:
@@ -641,6 +669,7 @@ int ext2_make_empty(struct inode *inode, struct inode *parent)
*/
int ext2_empty_dir (struct inode * inode)
{
+ void *page_addr = NULL;
struct page *page = NULL;
unsigned long i, npages = dir_pages(inode);
int dir_has_error = 0;
@@ -648,14 +677,14 @@ int ext2_empty_dir (struct inode * inode)
for (i = 0; i < npages; i++) {
char *kaddr;
ext2_dirent * de;
- page = ext2_get_page(inode, i, dir_has_error);
+ page = ext2_get_page(inode, i, dir_has_error, &page_addr);
if (IS_ERR(page)) {
dir_has_error = 1;
continue;
}
- kaddr = page_address(page);
+ kaddr = page_addr;
de = (ext2_dirent *)kaddr;
kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
@@ -681,12 +710,12 @@ int ext2_empty_dir (struct inode * inode)
}
de = ext2_next_entry(de);
}
- ext2_put_page(page);
+ ext2_put_page(page, page_addr);
}
return 1;
not_empty:
- ext2_put_page(page);
+ ext2_put_page(page, page_addr);
return 0;
}
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 3309fb2d327a..ad01ef997926 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -742,14 +742,16 @@ extern int ext2_add_link (struct dentry *, struct inode *);
extern int ext2_inode_by_name(struct inode *dir,
const struct qstr *child, ino_t *ino);
extern int ext2_make_empty(struct inode *, struct inode *);
-extern struct ext2_dir_entry_2 * ext2_find_entry (struct inode *,const struct qstr *, struct page **);
+extern struct ext2_dir_entry_2 *ext2_find_entry(struct inode *, const struct qstr *,
+ struct page **, void **res_page_addr);
extern int ext2_delete_entry (struct ext2_dir_entry_2 *, struct page *);
extern int ext2_empty_dir (struct inode *);
-extern struct ext2_dir_entry_2 * ext2_dotdot (struct inode *, struct page **);
-extern void ext2_set_link(struct inode *, struct ext2_dir_entry_2 *, struct page *, struct inode *, int);
-static inline void ext2_put_page(struct page *page)
+extern struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct page **p, void **pa);
+extern void ext2_set_link(struct inode *, struct ext2_dir_entry_2 *, struct page *, void *,
+ struct inode *, int);
+static inline void ext2_put_page(struct page *page, void *page_addr)
{
- kunmap(page);
+ kunmap_local(page_addr);
put_page(page);
}
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index 7af9ab3f975e..c45e175bea9c 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -281,20 +281,21 @@ static int ext2_unlink(struct inode * dir, struct dentry *dentry)
struct inode * inode = d_inode(dentry);
struct ext2_dir_entry_2 * de;
struct page * page;
+ void *page_addr;
int err;
err = dquot_initialize(dir);
if (err)
goto out;
- de = ext2_find_entry(dir, &dentry->d_name, &page);
+ de = ext2_find_entry(dir, &dentry->d_name, &page, &page_addr);
if (IS_ERR(de)) {
err = PTR_ERR(de);
goto out;
}
err = ext2_delete_entry (de, page);
- ext2_put_page(page);
+ ext2_put_page(page, page_addr);
if (err)
goto out;
@@ -329,8 +330,10 @@ static int ext2_rename (struct user_namespace * mnt_userns,
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 ext2_dir_entry_2 * dir_de = NULL;
struct page * old_page;
+ void *old_page_addr;
struct ext2_dir_entry_2 * old_de;
int err;
@@ -345,7 +348,8 @@ static int ext2_rename (struct user_namespace * mnt_userns,
if (err)
goto out;
- old_de = ext2_find_entry(old_dir, &old_dentry->d_name, &old_page);
+ old_de = ext2_find_entry(old_dir, &old_dentry->d_name, &old_page,
+ &old_page_addr);
if (IS_ERR(old_de)) {
err = PTR_ERR(old_de);
goto out;
@@ -353,12 +357,13 @@ static int ext2_rename (struct user_namespace * mnt_userns,
if (S_ISDIR(old_inode->i_mode)) {
err = -EIO;
- dir_de = ext2_dotdot(old_inode, &dir_page);
+ dir_de = ext2_dotdot(old_inode, &dir_page, &dir_page_addr);
if (!dir_de)
goto out_old;
}
if (new_inode) {
+ void *page_addr;
struct page *new_page;
struct ext2_dir_entry_2 *new_de;
@@ -366,13 +371,14 @@ static int ext2_rename (struct user_namespace * mnt_userns,
if (dir_de && !ext2_empty_dir (new_inode))
goto out_dir;
- new_de = ext2_find_entry(new_dir, &new_dentry->d_name, &new_page);
+ new_de = ext2_find_entry(new_dir, &new_dentry->d_name,
+ &new_page, &page_addr);
if (IS_ERR(new_de)) {
err = PTR_ERR(new_de);
goto out_dir;
}
- ext2_set_link(new_dir, new_de, new_page, old_inode, 1);
- ext2_put_page(new_page);
+ ext2_set_link(new_dir, new_de, new_page, page_addr, old_inode, 1);
+ ext2_put_page(new_page, page_addr);
new_inode->i_ctime = current_time(new_inode);
if (dir_de)
drop_nlink(new_inode);
@@ -392,24 +398,25 @@ static int ext2_rename (struct user_namespace * mnt_userns,
old_inode->i_ctime = current_time(old_inode);
mark_inode_dirty(old_inode);
- ext2_delete_entry (old_de, old_page);
- ext2_put_page(old_page);
+ ext2_delete_entry(old_de, old_page);
if (dir_de) {
if (old_dir != new_dir)
- ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
+ ext2_set_link(old_inode, dir_de, dir_page,
+ dir_page_addr, new_dir, 0);
- ext2_put_page(dir_page);
+ ext2_put_page(dir_page, dir_page_addr);
inode_dec_link_count(old_dir);
}
- return 0;
+ ext2_put_page(old_page, old_page_addr);
+ return 0;
out_dir:
if (dir_de)
- ext2_put_page(dir_page);
+ ext2_put_page(dir_page, dir_page_addr);
out_old:
- ext2_put_page(old_page);
+ ext2_put_page(old_page, old_page_addr);
out:
return err;
}
--
2.28.0.rc0.12.gb6a658bd00c9
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