[PATCH v2] fs/netfs/fscache_io: remove the obsolete "using_pgpriv2" flag
From: Max Kellermann
Date: Mon Jul 29 2024 - 05:28:53 EST
This fixes a crash bug caused by commit ae678317b95e ("netfs: Remove
deprecated use of PG_private_2 as a second writeback flag") by
removing a leftover folio_end_private_2() call after all calls to
folio_start_private_2() had been removed by the commit.
By calling folio_end_private_2() without folio_start_private_2(), the
folio refcounter breaks and causes trouble like RCU stalls and general
protection faults.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: ae678317b95e ("netfs: Remove deprecated use of PG_private_2 as a second writeback flag")
Link: https://lore.kernel.org/ceph-devel/CAKPOu+_DA8XiMAA2ApMj7Pyshve_YWknw8Hdt1=zCy9Y87R1qw@xxxxxxxxxxxxxx/
Signed-off-by: Max Kellermann <max.kellermann@xxxxxxxxx>
---
fs/ceph/addr.c | 2 +-
fs/netfs/fscache_io.c | 29 +----------------------------
include/linux/fscache.h | 30 ++++--------------------------
3 files changed, 6 insertions(+), 55 deletions(-)
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 8c16bc5250ef..485cbd1730d1 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -512,7 +512,7 @@ static void ceph_fscache_write_to_cache(struct inode *inode, u64 off, u64 len, b
struct fscache_cookie *cookie = ceph_fscache_cookie(ci);
fscache_write_to_cache(cookie, inode->i_mapping, off, len, i_size_read(inode),
- ceph_fscache_write_terminated, inode, true, caching);
+ ceph_fscache_write_terminated, inode, caching);
}
#else
static inline void ceph_fscache_write_to_cache(struct inode *inode, u64 off, u64 len, bool caching)
diff --git a/fs/netfs/fscache_io.c b/fs/netfs/fscache_io.c
index 38637e5c9b57..0d8f3f646598 100644
--- a/fs/netfs/fscache_io.c
+++ b/fs/netfs/fscache_io.c
@@ -166,30 +166,10 @@ struct fscache_write_request {
loff_t start;
size_t len;
bool set_bits;
- bool using_pgpriv2;
netfs_io_terminated_t term_func;
void *term_func_priv;
};
-void __fscache_clear_page_bits(struct address_space *mapping,
- loff_t start, size_t len)
-{
- pgoff_t first = start / PAGE_SIZE;
- pgoff_t last = (start + len - 1) / PAGE_SIZE;
- struct page *page;
-
- if (len) {
- XA_STATE(xas, &mapping->i_pages, first);
-
- rcu_read_lock();
- xas_for_each(&xas, page, last) {
- folio_end_private_2(page_folio(page));
- }
- rcu_read_unlock();
- }
-}
-EXPORT_SYMBOL(__fscache_clear_page_bits);
-
/*
* Deal with the completion of writing the data to the cache.
*/
@@ -198,10 +178,6 @@ static void fscache_wreq_done(void *priv, ssize_t transferred_or_error,
{
struct fscache_write_request *wreq = priv;
- if (wreq->using_pgpriv2)
- fscache_clear_page_bits(wreq->mapping, wreq->start, wreq->len,
- wreq->set_bits);
-
if (wreq->term_func)
wreq->term_func(wreq->term_func_priv, transferred_or_error,
was_async);
@@ -214,7 +190,7 @@ void __fscache_write_to_cache(struct fscache_cookie *cookie,
loff_t start, size_t len, loff_t i_size,
netfs_io_terminated_t term_func,
void *term_func_priv,
- bool using_pgpriv2, bool cond)
+ bool cond)
{
struct fscache_write_request *wreq;
struct netfs_cache_resources *cres;
@@ -232,7 +208,6 @@ void __fscache_write_to_cache(struct fscache_cookie *cookie,
wreq->mapping = mapping;
wreq->start = start;
wreq->len = len;
- wreq->using_pgpriv2 = using_pgpriv2;
wreq->set_bits = cond;
wreq->term_func = term_func;
wreq->term_func_priv = term_func_priv;
@@ -260,8 +235,6 @@ void __fscache_write_to_cache(struct fscache_cookie *cookie,
abandon_free:
kfree(wreq);
abandon:
- if (using_pgpriv2)
- fscache_clear_page_bits(mapping, start, len, cond);
if (term_func)
term_func(term_func_priv, ret, false);
}
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 9de27643607f..f8c52bddaa15 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -177,8 +177,7 @@ void __fscache_write_to_cache(struct fscache_cookie *cookie,
loff_t start, size_t len, loff_t i_size,
netfs_io_terminated_t term_func,
void *term_func_priv,
- bool using_pgpriv2, bool cond);
-extern void __fscache_clear_page_bits(struct address_space *, loff_t, size_t);
+ bool cond);
/**
* fscache_acquire_volume - Register a volume as desiring caching services
@@ -573,24 +572,6 @@ int fscache_write(struct netfs_cache_resources *cres,
return ops->write(cres, start_pos, iter, term_func, term_func_priv);
}
-/**
- * fscache_clear_page_bits - Clear the PG_fscache bits from a set of pages
- * @mapping: The netfs inode to use as the source
- * @start: The start position in @mapping
- * @len: The amount of data to unlock
- * @caching: If PG_fscache has been set
- *
- * Clear the PG_fscache flag from a sequence of pages and wake up anyone who's
- * waiting.
- */
-static inline void fscache_clear_page_bits(struct address_space *mapping,
- loff_t start, size_t len,
- bool caching)
-{
- if (caching)
- __fscache_clear_page_bits(mapping, start, len);
-}
-
/**
* fscache_write_to_cache - Save a write to the cache and clear PG_fscache
* @cookie: The cookie representing the cache object
@@ -600,7 +581,6 @@ static inline void fscache_clear_page_bits(struct address_space *mapping,
* @i_size: The new size of the inode
* @term_func: The function to call upon completion
* @term_func_priv: The private data for @term_func
- * @using_pgpriv2: If we're using PG_private_2 to mark in-progress write
* @caching: If we actually want to do the caching
*
* Helper function for a netfs to write dirty data from an inode into the cache
@@ -612,21 +592,19 @@ static inline void fscache_clear_page_bits(struct address_space *mapping,
* marked with PG_fscache.
*
* If given, @term_func will be called upon completion and supplied with
- * @term_func_priv. Note that if @using_pgpriv2 is set, the PG_private_2 flags
- * will have been cleared by this point, so the netfs must retain its own pin
- * on the mapping.
+ * @term_func_priv.
*/
static inline void fscache_write_to_cache(struct fscache_cookie *cookie,
struct address_space *mapping,
loff_t start, size_t len, loff_t i_size,
netfs_io_terminated_t term_func,
void *term_func_priv,
- bool using_pgpriv2, bool caching)
+ bool caching)
{
if (caching)
__fscache_write_to_cache(cookie, mapping, start, len, i_size,
term_func, term_func_priv,
- using_pgpriv2, caching);
+ caching);
else if (term_func)
term_func(term_func_priv, -ENOBUFS, false);
--
2.43.0