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Message-ID: <160392379129.592578.15917327277370370590.stgit@warthog.procyon.org.uk>
Date: Wed, 28 Oct 2020 22:23:11 +0000
From: David Howells <dhowells@...hat.com>
To: linux-afs@...ts.infradead.org
Cc: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
dhowells@...hat.com, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 05/11] afs: Fix to take ref on page when PG_private is set
Fix afs to take a ref on a page when it sets PG_private on it and to drop
the ref when removing the flag.
Note that in afs_write_begin(), a lot of the time, PG_private is already
set on a page to which we're going to add some data. In such a case, we
leave the bit set and mustn't increment the page count.
As suggested by Matthew Wilcox, use attach/detach_page_private() where
possible.
Fixes: 31143d5d515e ("AFS: implement basic file write support")
Reported-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Signed-off-by: David Howells <dhowells@...hat.com>
---
fs/afs/dir.c | 12 ++++--------
fs/afs/dir_edit.c | 6 ++----
fs/afs/file.c | 6 ++----
fs/afs/write.c | 17 ++++++++++-------
4 files changed, 18 insertions(+), 23 deletions(-)
diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 1d2e61e0ab04..1bb5b9d7f0a2 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -281,8 +281,7 @@ static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key)
if (ret < 0)
goto error;
- set_page_private(req->pages[i], 1);
- SetPagePrivate(req->pages[i]);
+ attach_page_private(req->pages[i], (void *)1);
unlock_page(req->pages[i]);
i++;
} else {
@@ -1975,8 +1974,7 @@ static int afs_dir_releasepage(struct page *page, gfp_t gfp_flags)
_enter("{{%llx:%llu}[%lu]}", dvnode->fid.vid, dvnode->fid.vnode, page->index);
- set_page_private(page, 0);
- ClearPagePrivate(page);
+ detach_page_private(page);
/* The directory will need reloading. */
if (test_and_clear_bit(AFS_VNODE_DIR_VALID, &dvnode->flags))
@@ -2003,8 +2001,6 @@ static void afs_dir_invalidatepage(struct page *page, unsigned int offset,
afs_stat_v(dvnode, n_inval);
/* we clean up only if the entire page is being invalidated */
- if (offset == 0 && length == PAGE_SIZE) {
- set_page_private(page, 0);
- ClearPagePrivate(page);
- }
+ if (offset == 0 && length == PAGE_SIZE)
+ detach_page_private(page);
}
diff --git a/fs/afs/dir_edit.c b/fs/afs/dir_edit.c
index b108528bf010..2ffe09abae7f 100644
--- a/fs/afs/dir_edit.c
+++ b/fs/afs/dir_edit.c
@@ -243,10 +243,8 @@ void afs_edit_dir_add(struct afs_vnode *vnode,
index, gfp);
if (!page)
goto error;
- if (!PagePrivate(page)) {
- set_page_private(page, 1);
- SetPagePrivate(page);
- }
+ if (!PagePrivate(page))
+ attach_page_private(page, (void *)1);
dir_page = kmap(page);
}
diff --git a/fs/afs/file.c b/fs/afs/file.c
index 91225421ad37..4503c493dddb 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -630,8 +630,7 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
priv = page_private(page);
trace_afs_page_dirty(vnode, tracepoint_string("inval"),
page->index, priv);
- set_page_private(page, 0);
- ClearPagePrivate(page);
+ detach_page_private(page);
}
}
@@ -664,8 +663,7 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags)
priv = page_private(page);
trace_afs_page_dirty(vnode, tracepoint_string("rel"),
page->index, priv);
- set_page_private(page, 0);
- ClearPagePrivate(page);
+ detach_page_private(page);
}
/* indicate that the page can be released */
diff --git a/fs/afs/write.c b/fs/afs/write.c
index b937ec047ec9..50d5ff4ad70d 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -151,8 +151,10 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
priv |= f;
trace_afs_page_dirty(vnode, tracepoint_string("begin"),
page->index, priv);
- SetPagePrivate(page);
- set_page_private(page, priv);
+ if (PagePrivate(page))
+ set_page_private(page, priv);
+ else
+ attach_page_private(page, (void *)priv);
_leave(" = 0");
return 0;
@@ -337,7 +339,7 @@ static void afs_pages_written_back(struct afs_vnode *vnode,
priv = page_private(pv.pages[loop]);
trace_afs_page_dirty(vnode, tracepoint_string("clear"),
pv.pages[loop]->index, priv);
- set_page_private(pv.pages[loop], 0);
+ detach_page_private(pv.pages[loop]);
end_page_writeback(pv.pages[loop]);
}
first += count;
@@ -863,8 +865,10 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
priv |= 0; /* From */
trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
vmf->page->index, priv);
- SetPagePrivate(vmf->page);
- set_page_private(vmf->page, priv);
+ if (PagePrivate(vmf->page))
+ set_page_private(vmf->page, priv);
+ else
+ attach_page_private(vmf->page, (void *)priv);
file_update_time(file);
sb_end_pagefault(inode->i_sb);
@@ -928,8 +932,7 @@ int afs_launder_page(struct page *page)
trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
page->index, priv);
- set_page_private(page, 0);
- ClearPagePrivate(page);
+ detach_page_private(page);
#ifdef CONFIG_AFS_FSCACHE
if (PageFsCache(page)) {
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