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ubifs: Convert ubifs_vm_page_mkwrite() to use a folio 

Replace six implicit calls to compound_head() with one.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Matthew Wilcox (Oracle) 2024-01-24 17:52:49 +00:00 committed by Richard Weinberger
parent 0c2d140c1f
commit 85ffbf5557
2 changed files with 28 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
Documentation/mm/page_cache.rst
View File

@ -3,3 +3,13 @@
==========
Page Cache
==========
The page cache is the primary way that the user and the rest of the kernel
interact with filesystems. It can be bypassed (e.g. with O_DIRECT),
but normal reads, writes and mmaps go through the page cache.
Folios
======
The folio is the unit of memory management within the page cache.
Operations

36
fs/ubifs/file.c
View File

@ -1514,14 +1514,14 @@ static bool ubifs_release_folio(struct folio *folio, gfp_t unused_gfp_flags)
*/
static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf)
{
struct page *page = vmf->page;
struct folio *folio = page_folio(vmf->page);
struct inode *inode = file_inode(vmf->vma->vm_file);
struct ubifs_info *c = inode->i_sb->s_fs_info;
struct timespec64 now = current_time(inode);
struct ubifs_budget_req req = { .new_page = 1 };
int err, update_time;
dbg_gen("ino %lu, pg %lu, i_size %lld", inode->i_ino, page->index,
dbg_gen("ino %lu, pg %lu, i_size %lld", inode->i_ino, folio->index,
i_size_read(inode));
ubifs_assert(c, !c->ro_media && !c->ro_mount);
@ -1529,17 +1529,17 @@ static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf)
return VM_FAULT_SIGBUS; /* -EROFS */
/*
* We have not locked @page so far so we may budget for changing the
* page. Note, we cannot do this after we locked the page, because
* We have not locked @folio so far so we may budget for changing the
* folio. Note, we cannot do this after we locked the folio, because
* budgeting may cause write-back which would cause deadlock.
*
* At the moment we do not know whether the page is dirty or not, so we
* assume that it is not and budget for a new page. We could look at
* At the moment we do not know whether the folio is dirty or not, so we
* assume that it is not and budget for a new folio. We could look at
* the @PG_private flag and figure this out, but we may race with write
* back and the page state may change by the time we lock it, so this
* back and the folio state may change by the time we lock it, so this
* would need additional care. We do not bother with this at the
* moment, although it might be good idea to do. Instead, we allocate
* budget for a new page and amend it later on if the page was in fact
* budget for a new folio and amend it later on if the folio was in fact
* dirty.
*
* The budgeting-related logic of this function is similar to what we
@ -1562,21 +1562,21 @@ static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf)
return VM_FAULT_SIGBUS;
}
lock_page(page);
if (unlikely(page->mapping != inode->i_mapping ||
page_offset(page) > i_size_read(inode))) {
/* Page got truncated out from underneath us */
folio_lock(folio);
if (unlikely(folio->mapping != inode->i_mapping ||
folio_pos(folio) >= i_size_read(inode))) {
/* Folio got truncated out from underneath us */
goto sigbus;
}
if (PagePrivate(page))
if (folio->private)
release_new_page_budget(c);
else {
if (!PageChecked(page))
if (!folio_test_checked(folio))
ubifs_convert_page_budget(c);
attach_page_private(page, (void *)1);
folio_attach_private(folio, (void *)1);
atomic_long_inc(&c->dirty_pg_cnt);
__set_page_dirty_nobuffers(page);
filemap_dirty_folio(folio->mapping, folio);
}
if (update_time) {
@ -1592,11 +1592,11 @@ static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf)
ubifs_release_dirty_inode_budget(c, ui);
}
wait_for_stable_page(page);
folio_wait_stable(folio);
return VM_FAULT_LOCKED;
sigbus:
unlock_page(page);
folio_unlock(folio);
ubifs_release_budget(c, &req);
return VM_FAULT_SIGBUS;
}