diff options
author | Ira Weiny <ira.weiny@intel.com> | 2021-03-28 23:54:02 -0700 |
---|---|---|
committer | Jan Kara <jack@suse.cz> | 2021-03-31 13:10:20 +0200 |
commit | 782b76d7abdf02b12c46ed6f1e9bf715569027f7 (patch) | |
tree | ff01e154cd08335de0da0f1cf8fae5262202f61c /fs/ext2/dir.c | |
parent | e2ebb1230455985df6aa45835a451a5404eddd8d (diff) | |
download | linux-782b76d7abdf02b12c46ed6f1e9bf715569027f7.tar.bz2 |
fs/ext2: Replace kmap() with kmap_local_page()
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@suse.com>
Link: https://lore.kernel.org/r/20210329065402.3297092-3-ira.weiny@intel.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/ext2/dir.c')
-rw-r--r-- | fs/ext2/dir.c | 89 |
1 files changed, 59 insertions, 30 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 @@ fail: 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 @@ out: found: *res_page = page; + *res_page_addr = page_addr; ei->i_dir_start_lookup = n; return de; } @@ -402,15 +418,24 @@ found: * (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 @@ got_it: 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 @@ fail: */ 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; } |