From: David Howells <dhowells@redhat.com>
Date: Wed, 20 Oct 2021 14:06:34 +0100
Subject: fscache: Provide a function to resize a cookie
Git-commit: 16a96bdf92d5af06f9fa6a01a4b08e2fdfed2e5b
Patch-mainline: v5.17-rc1
References: jsc#SES-1880
Provide a function to change the size of the storage attached to a cookie,
to match the size of the file being cached when it's changed by truncate or
fallocate:
void fscache_resize_cookie(struct fscache_cookie *cookie,
loff_t new_size);
This acts synchronously and is expected to run under the inode lock of the
caller.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819621839.215744.7895597119803515402.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906922387.143852.16394459879816147793.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967128998.1823006.10740669081985775576.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021527861.640689.3466382085497236267.stgit@warthog.procyon.org.uk/ # v4
Acked-by: Luis Henriques <lhenriques@suse.com>
---
fs/fscache/internal.h | 3 +++
fs/fscache/io.c | 25 +++++++++++++++++++++++++
fs/fscache/stats.c | 9 +++++++--
include/linux/fscache-cache.h | 4 ++++
include/linux/fscache.h | 18 ++++++++++++++++++
include/trace/events/fscache.h | 25 +++++++++++++++++++++++++
6 files changed, 82 insertions(+), 2 deletions(-)
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index 017bf3d346a4..f121c21590dc 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -122,6 +122,9 @@ extern atomic_t fscache_n_relinquishes;
extern atomic_t fscache_n_relinquishes_retire;
extern atomic_t fscache_n_relinquishes_dropped;
+extern atomic_t fscache_n_resizes;
+extern atomic_t fscache_n_resizes_null;
+
static inline void fscache_stat(atomic_t *stat)
{
atomic_inc(stat);
diff --git a/fs/fscache/io.c b/fs/fscache/io.c
index e9e5d6758ea8..bed7628a5a9d 100644
--- a/fs/fscache/io.c
+++ b/fs/fscache/io.c
@@ -291,3 +291,28 @@ void __fscache_write_to_cache(struct fscache_cookie *cookie,
term_func(term_func_priv, ret, false);
}
EXPORT_SYMBOL(__fscache_write_to_cache);
+
+/*
+ * Change the size of a backing object.
+ */
+void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
+{
+ struct netfs_cache_resources cres;
+
+ trace_fscache_resize(cookie, new_size);
+ if (fscache_begin_operation(&cres, cookie, FSCACHE_WANT_WRITE,
+ fscache_access_io_resize) == 0) {
+ fscache_stat(&fscache_n_resizes);
+ set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);
+
+ /* We cannot defer a resize as we need to do it inside the
+ * netfs's inode lock so that we're serialised with respect to
+ * writes.
+ */
+ cookie->volume->cache->ops->resize_cookie(&cres, new_size);
+ fscache_end_operation(&cres);
+ } else {
+ fscache_stat(&fscache_n_resizes_null);
+ }
+}
+EXPORT_SYMBOL(__fscache_resize_cookie);
diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
index db42beb1ba3f..798ee68b3e9d 100644
--- a/fs/fscache/stats.c
+++ b/fs/fscache/stats.c
@@ -35,6 +35,9 @@ atomic_t fscache_n_relinquishes;
atomic_t fscache_n_relinquishes_retire;
atomic_t fscache_n_relinquishes_dropped;
+atomic_t fscache_n_resizes;
+atomic_t fscache_n_resizes_null;
+
atomic_t fscache_n_read;
EXPORT_SYMBOL(fscache_n_read);
atomic_t fscache_n_write;
@@ -69,8 +72,10 @@ int fscache_stats_show(struct seq_file *m, void *v)
seq_printf(m, "Invals : n=%u\n",
atomic_read(&fscache_n_invalidates));
- seq_printf(m, "Updates: n=%u\n",
- atomic_read(&fscache_n_updates));
+ seq_printf(m, "Updates: n=%u rsz=%u rsn=%u\n",
+ atomic_read(&fscache_n_updates),
+ atomic_read(&fscache_n_resizes),
+ atomic_read(&fscache_n_resizes_null));
seq_printf(m, "Relinqs: n=%u rtr=%u drop=%u\n",
atomic_read(&fscache_n_relinquishes),
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 796c8b5c5305..3fa4902dc87c 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -64,6 +64,10 @@ struct fscache_cache_ops {
/* Withdraw an object without any cookie access counts held */
void (*withdraw_cookie)(struct fscache_cookie *cookie);
+ /* Change the size of a data object */
+ void (*resize_cookie)(struct netfs_cache_resources *cres,
+ loff_t new_size);
+
/* Invalidate an object */
bool (*invalidate_cookie)(struct fscache_cookie *cookie);
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 28ce258c1f87..86b1c0db1de5 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -163,6 +163,7 @@ extern struct fscache_cookie *__fscache_acquire_cookie(
extern void __fscache_use_cookie(struct fscache_cookie *, bool);
extern void __fscache_unuse_cookie(struct fscache_cookie *, const void *, const loff_t *);
extern void __fscache_relinquish_cookie(struct fscache_cookie *, bool);
+extern void __fscache_resize_cookie(struct fscache_cookie *, loff_t);
extern void __fscache_invalidate(struct fscache_cookie *, const void *, loff_t, unsigned int);
extern int __fscache_begin_read_operation(struct netfs_cache_resources *, struct fscache_cookie *);
@@ -366,6 +367,23 @@ void fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data,
__fscache_update_cookie(cookie, aux_data, object_size);
}
+/**
+ * fscache_resize_cookie - Request that a cache object be resized
+ * @cookie: The cookie representing the cache object
+ * @new_size: The new size of the object (may be NULL)
+ *
+ * Request that the size of an object be changed.
+ *
+ * See Documentation/filesystems/caching/netfs-api.txt for a complete
+ * description.
+ */
+static inline
+void fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
+{
+ if (fscache_cookie_enabled(cookie))
+ __fscache_resize_cookie(cookie, new_size);
+}
+
/**
* fscache_invalidate - Notify cache that an object needs invalidation
* @cookie: The cookie representing the cache object
diff --git a/include/trace/events/fscache.h b/include/trace/events/fscache.h
index 2459d75659cf..5fa37a8b4ec7 100644
--- a/include/trace/events/fscache.h
+++ b/include/trace/events/fscache.h
@@ -78,6 +78,7 @@ enum fscache_access_trace {
fscache_access_invalidate_cookie_end,
fscache_access_io_not_live,
fscache_access_io_read,
+ fscache_access_io_resize,
fscache_access_io_wait,
fscache_access_io_write,
fscache_access_lookup_cookie,
@@ -149,6 +150,7 @@ enum fscache_access_trace {
EM(fscache_access_invalidate_cookie_end,"END inval ") \
EM(fscache_access_io_not_live, "END io_notl") \
EM(fscache_access_io_read, "BEGIN io_read") \
+ EM(fscache_access_io_resize, "BEGIN io_resz") \
EM(fscache_access_io_wait, "WAIT io ") \
EM(fscache_access_io_write, "BEGIN io_writ") \
EM(fscache_access_lookup_cookie, "BEGIN lookup ") \
@@ -418,6 +420,29 @@ TRACE_EVENT(fscache_invalidate,
__entry->cookie, __entry->new_size)
);
+TRACE_EVENT(fscache_resize,
+ TP_PROTO(struct fscache_cookie *cookie, loff_t new_size),
+
+ TP_ARGS(cookie, new_size),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, cookie )
+ __field(loff_t, old_size )
+ __field(loff_t, new_size )
+ ),
+
+ TP_fast_assign(
+ __entry->cookie = cookie->debug_id;
+ __entry->old_size = cookie->object_size;
+ __entry->new_size = new_size;
+ ),
+
+ TP_printk("c=%08x os=%08llx sz=%08llx",
+ __entry->cookie,
+ __entry->old_size,
+ __entry->new_size)
+ );
+
#endif /* _TRACE_FSCACHE_H */
/* This part must be outside protection */