From: David Howells <dhowells@redhat.com>
To: Trond Myklebust <trondmy@hammerspace.com>,
Anna Schumaker <anna.schumaker@netapp.com>,
Steve French <sfrench@samba.org>,
Dominique Martinet <asmadeus@codewreck.org>
Cc: dhowells@redhat.com, Jeff Layton <jlayton@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-cachefs@redhat.com, linux-afs@lists.infradead.org,
linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org,
ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC PATCH 69/76] fscache: Add support for writing to the cache
Date: Fri, 20 Nov 2020 15:17:32 +0000 [thread overview]
Message-ID: <160588545208.3465195.7723308498025669512.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <160588455242.3465195.3214733858273019178.stgit@warthog.procyon.org.uk>
Add a pair of helpers for use by a netfs to write data to the cache.
Signed-off-by: David Howells <dhowells@redhat.com>
---
fs/cachefiles/content-map.c | 38 +++++++++++++
fs/cachefiles/interface.c | 1
fs/cachefiles/internal.h | 2 +
fs/fscache/io.c | 128 +++++++++++++++++++++++++++++++++++++++++++
include/linux/fscache.h | 34 +++++++++++
5 files changed, 203 insertions(+)
diff --git a/fs/cachefiles/content-map.c b/fs/cachefiles/content-map.c
index da0a81e3f751..d1e8a509a8cc 100644
--- a/fs/cachefiles/content-map.c
+++ b/fs/cachefiles/content-map.c
@@ -204,6 +204,44 @@ enum netfs_read_source cachefiles_prepare_read(struct netfs_read_subrequest *sub
return NETFS_READ_FROM_CACHE;
}
+/*
+ * Prepare for a write to occur.
+ */
+int cachefiles_prepare_write(struct fscache_op_resources *opr,
+ loff_t *_start, size_t *_len, loff_t i_size)
+{
+ struct cachefiles_object *object =
+ container_of(opr->object, struct cachefiles_object, fscache);
+ loff_t start = *_start, map_limit;
+ size_t len = *_len, down;
+ long granule = start / CACHEFILES_GRAN_SIZE;
+
+ if (start >= CACHEFILES_SIZE_LIMIT)
+ return -ENOBUFS;
+
+ if (granule / 8 >= object->content_map_size) {
+ cachefiles_expand_content_map(object, i_size);
+ if (granule / 8 >= object->content_map_size)
+ return -ENOBUFS;
+ }
+
+ map_limit = object->content_map_size * 8 * CACHEFILES_GRAN_SIZE;
+ if (start >= map_limit)
+ return -ENOBUFS;
+ if (len > map_limit - start)
+ len = map_limit - start;
+
+ /* Assume that the preparation to write involved preloading any
+ * bits of the cache that weren't to be written and filling any
+ * gaps that didn't end up being written.
+ */
+
+ down = start - round_down(start, CACHEFILES_DIO_BLOCK_SIZE);
+ *_start = start - down;
+ *_len = round_up(down + len, CACHEFILES_DIO_BLOCK_SIZE);
+ return 0;
+}
+
/*
* Allocate a new content map.
*/
diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 3609ff2fb491..a9725ca72ad5 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -609,6 +609,7 @@ static const struct fscache_op_ops cachefiles_io_ops = {
.write = cachefiles_write,
.expand_readahead = cachefiles_expand_readahead,
.prepare_read = cachefiles_prepare_read,
+ .prepare_write = cachefiles_prepare_write,
};
static void cachefiles_begin_operation(struct fscache_op_resources *opr)
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index e2d06c0860a2..38149868c331 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -137,6 +137,8 @@ extern void cachefiles_mark_content_map(struct cachefiles_object *object,
loff_t start, loff_t len, unsigned int inval_counter);
extern void cachefiles_expand_content_map(struct cachefiles_object *object, loff_t size);
extern void cachefiles_shorten_content_map(struct cachefiles_object *object, loff_t new_size);
+extern int cachefiles_prepare_write(struct fscache_op_resources *opr,
+ loff_t *_start, size_t *_len, loff_t i_size);
extern bool cachefiles_load_content_map(struct cachefiles_object *object);
extern void cachefiles_save_content_map(struct cachefiles_object *object);
extern int cachefiles_display_object(struct seq_file *m, struct fscache_object *object);
diff --git a/fs/fscache/io.c b/fs/fscache/io.c
index 5401c9ed347b..295a89af4269 100644
--- a/fs/fscache/io.c
+++ b/fs/fscache/io.c
@@ -10,6 +10,7 @@
#include <linux/fscache-cache.h>
#include <linux/slab.h>
#include <linux/netfs.h>
+#include <linux/uio.h>
#include "internal.h"
/*
@@ -260,3 +261,130 @@ void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
}
}
EXPORT_SYMBOL(__fscache_resize_cookie);
+
+struct fscache_write_request {
+ struct fscache_op_resources cache_resources;
+ struct address_space *mapping;
+ loff_t start;
+ size_t len;
+ fscache_io_terminated_t term_func;
+ void *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
+ *
+ * Clear the PG_fscache flag from a sequence of pages and wake up anyone who's
+ * waiting.
+ */
+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) {
+ unlock_page_fscache(page);
+ }
+ rcu_read_unlock();
+ }
+}
+EXPORT_SYMBOL(__fscache_clear_page_bits);
+
+/*
+ * Deal with the completion of writing the data to the cache.
+ */
+static void fscache_wreq_done(void *priv, ssize_t transferred_or_error)
+{
+ struct fscache_write_request *wreq = priv;
+
+ fscache_clear_page_bits(wreq->mapping, wreq->start, wreq->len);
+
+ if (wreq->term_func)
+ wreq->term_func(wreq->term_func_priv, transferred_or_error);
+ fscache_end_operation(&wreq->cache_resources);
+ kfree(wreq);
+}
+
+/**
+ * fscache_write_to_cache - Save a write to the cache and clear PG_fscache
+ * @cookie: The cookie representing the cache object
+ * @mapping: The netfs inode to use as the source
+ * @start: The start position in @mapping
+ * @len: The amount of data to write back
+ * @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
+ *
+ * Helper function for a netfs to write dirty data from an inode into the cache
+ * object that's backing it.
+ *
+ * @start and @len describe the range of the data. This does not need to be
+ * page-aligned, but to satisfy DIO requirements, the cache may expand it up to
+ * the page boundaries on either end. All the pages covering the range must be
+ * marked with PG_fscache.
+ *
+ * If given, @term_func will be called upon completion and supplied with
+ * @term_func_priv. Note that the PG_fscache flags will have been cleared by
+ * this point, so the netfs must retain its own pin on the mapping.
+ */
+void __fscache_write_to_cache(struct fscache_cookie *cookie,
+ struct address_space *mapping,
+ loff_t start, size_t len, loff_t i_size,
+ fscache_io_terminated_t term_func,
+ void *term_func_priv)
+{
+ struct fscache_write_request *wreq;
+ struct fscache_op_resources *opr;
+ struct iov_iter iter;
+ int ret = -ENOBUFS;
+
+ if (!fscache_cookie_valid(cookie) || len == 0)
+ goto abandon;
+
+ _enter("%llx,%zx", start, len);
+
+ wreq = kzalloc(sizeof(struct fscache_write_request), GFP_NOFS);
+ if (!wreq)
+ goto abandon;
+ wreq->mapping = mapping;
+ wreq->start = start;
+ wreq->len = len;
+ wreq->term_func = term_func;
+ wreq->term_func_priv = term_func_priv;
+
+ opr = &wreq->cache_resources;
+ if (fscache_begin_operation(cookie, opr, FSCACHE_WANT_WRITE) < 0)
+ goto abandon_free;
+
+ ret = opr->ops->prepare_write(opr, &start, &len, i_size);
+ if (ret < 0)
+ goto abandon_end;
+
+ /* TODO: Consider clearing page bits now for space the write isn't
+ * covering. This is more complicated than it appears when THPs are
+ * taken into account.
+ */
+
+ iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
+ fscache_write(opr, start, &iter, fscache_wreq_done, wreq);
+ return;
+
+abandon_end:
+ return fscache_wreq_done(wreq, ret);
+abandon_free:
+ kfree(wreq);
+abandon:
+ fscache_clear_page_bits(mapping, start, len);
+ if (term_func)
+ term_func(term_func_priv, ret);
+}
+EXPORT_SYMBOL(__fscache_write_to_cache);
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 1c1ea3558421..0613ccea88c1 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -192,6 +192,12 @@ struct fscache_op_ops {
*/
enum netfs_read_source (*prepare_read)(struct netfs_read_subrequest *subreq,
loff_t i_size);
+
+ /* Prepare a write operation, working out what part of the write we can
+ * actually do.
+ */
+ int (*prepare_write)(struct fscache_op_resources *opr,
+ loff_t *_start, size_t *_len, loff_t i_size);
};
/*
@@ -226,6 +232,10 @@ extern void __fscache_invalidate(struct fscache_cookie *, const void *, loff_t,
extern void fscache_put_super(struct super_block *,
struct fscache_cookie *(*get_cookie)(struct inode *));
+extern void __fscache_write_to_cache(struct fscache_cookie *, struct address_space *,
+ loff_t, size_t, loff_t, fscache_io_terminated_t, void *);
+extern void __fscache_clear_page_bits(struct address_space *, loff_t, size_t);
+
/**
* fscache_register_netfs - Register a filesystem as desiring caching services
* @netfs: The description of the filesystem
@@ -627,6 +637,30 @@ int fscache_write(struct fscache_op_resources *opr,
return ops->write(opr, start_pos, iter, term_func, term_func_priv);
}
+static inline void fscache_clear_page_bits(struct address_space *mapping,
+ loff_t start, size_t len)
+{
+ if (fscache_available())
+ __fscache_clear_page_bits(mapping, start, len);
+}
+
+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,
+ fscache_io_terminated_t term_func,
+ void *term_func_priv)
+{
+ if (fscache_available()) {
+ __fscache_write_to_cache(cookie, mapping, start, len, i_size,
+ term_func, term_func_priv);
+ } else {
+ fscache_clear_page_bits(mapping, start, len);
+ if (term_func)
+ term_func(term_func_priv, -ENOBUFS);
+ }
+
+}
+
#if __fscache_available
extern int fscache_set_page_dirty(struct page *page, struct fscache_cookie *cookie);
#else
next prev parent reply other threads:[~2020-11-20 15:18 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 15:02 [RFC PATCH 00/76] fscache: Modernisation David Howells
2020-11-20 15:02 ` [RFC PATCH 01/76] nfs, cifs, ceph, 9p: Disable use of fscache prior to its rewrite David Howells
2020-11-20 15:02 ` [RFC PATCH 02/76] afs: Disable use of the fscache I/O routines David Howells
2020-11-20 15:03 ` [RFC PATCH 03/76] fscache: Add a cookie debug ID and use that in traces David Howells
2020-11-20 15:03 ` [RFC PATCH 04/76] fscache: Procfile to display cookies David Howells
2020-11-20 15:03 ` [RFC PATCH 05/76] fscache: Remove the old I/O API David Howells
2020-11-20 15:03 ` [RFC PATCH 06/76] fscache: Remove the netfs data from the cookie David Howells
2020-11-20 15:04 ` [RFC PATCH 07/76] fscache: Remove struct fscache_cookie_def David Howells
2020-11-20 15:04 ` [RFC PATCH 08/76] fscache: Remove store_limit* from struct fscache_object David Howells
2020-11-20 15:04 ` [RFC PATCH 09/76] fscache: Remove fscache_check_consistency() David Howells
2020-11-20 15:04 ` [RFC PATCH 10/76] fscache: Remove fscache_attr_changed() David Howells
2020-11-20 15:04 ` [RFC PATCH 11/76] fscache: Remove obsolete stats David Howells
2020-11-20 15:05 ` [RFC PATCH 12/76] fscache: Remove old I/O tracepoints David Howells
2020-11-20 15:05 ` [RFC PATCH 13/76] fscache: Temporarily disable fscache_invalidate() David Howells
2020-11-20 15:05 ` [RFC PATCH 14/76] fscache: Remove the I/O operation manager David Howells
2020-11-20 15:05 ` [RFC PATCH 15/76] fscache: Change %p in format strings to something else David Howells
2020-11-20 15:06 ` [RFC PATCH 16/76] cachefiles: " David Howells
2020-11-20 15:06 ` [RFC PATCH 17/76] iov_iter: Add ITER_XARRAY David Howells
2020-11-20 15:06 ` [RFC PATCH 18/76] vm: Add wait/unlock functions for PG_fscache David Howells
2020-11-20 15:06 ` [RFC PATCH 19/76] mm: Implement readahead_control pageset expansion David Howells
2020-11-20 15:06 ` [RFC PATCH 20/76] mm: Stop generic_file_buffered_read() from grabbing a superfluous page David Howells
2020-11-20 15:07 ` [RFC PATCH 21/76] vfs: Export rw_verify_area() for use by cachefiles David Howells
2020-11-20 15:07 ` [RFC PATCH 22/76] vfs: Provide S_CACHE_FILE inode flag David Howells
2020-11-20 15:07 ` [RFC PATCH 23/76] cachefiles: Remove tree of active files and use " David Howells
2020-11-20 15:07 ` [RFC PATCH 24/76] fscache: Provide a simple thread pool for running ops asynchronously David Howells
2020-11-20 15:08 ` [RFC PATCH 26/76] fscache: Rewrite the I/O API based on iov_iter David Howells
2020-11-20 15:08 ` [RFC PATCH 27/76] fscache: Keep track of size of a file last set independently on the server David Howells
2020-11-20 15:08 ` [RFC PATCH 28/76] fscache, cachefiles: Fix disabled histogram warnings David Howells
2020-11-20 15:08 ` [RFC PATCH 29/76] fscache: Recast assertion in terms of cookie not being an index David Howells
2020-11-20 15:08 ` [RFC PATCH 30/76] vfs, fscache: Force ->write_inode() to occur if cookie pinned for writeback David Howells
2020-11-20 15:09 ` [RFC PATCH 31/76] fscache: Allow ->put_super() to be used to wait for cache operations David Howells
2020-11-20 15:09 ` [RFC PATCH 32/76] netfs: Make a netfs helper module David Howells
2020-11-20 15:09 ` [RFC PATCH 33/76] netfs: Provide readahead and readpage netfs helpers David Howells
2020-11-20 15:09 ` [RFC PATCH 34/76] netfs: Use the cache David Howells
2020-11-20 15:10 ` [RFC PATCH 35/76] fscache: read-helper: Add tracepoints David Howells
2020-11-20 15:10 ` [RFC PATCH 36/76] cachefiles: Remove some redundant checks on unsigned values David Howells
2020-11-20 15:10 ` [RFC PATCH 37/76] cachefiles: trace: Log coherency checks David Howells
2020-11-20 15:10 ` [RFC PATCH 38/76] cachefiles: Split cachefiles_drop_object() up a bit David Howells
2020-11-20 15:11 ` [RFC PATCH 39/76] cachefiles: Implement new fscache I/O backend API David Howells
2020-11-20 15:11 ` [RFC PATCH 40/76] cachefiles: Merge object->backer into object->dentry David Howells
2020-11-20 15:11 ` [RFC PATCH 41/76] cachefiles: Implement a content-present indicator and bitmap David Howells
2020-11-20 15:11 ` [RFC PATCH 42/76] cachefiles: Shape requests from the fscache read helper David Howells
2020-11-20 15:11 ` [RFC PATCH 43/76] cachefiles: Round the cachefile size up to DIO block size David Howells
2020-11-20 15:12 ` [RFC PATCH 44/76] cachefiles: Implement read and write parts of new I/O API David Howells
2020-11-20 15:12 ` [RFC PATCH 45/76] cachefiles: Add I/O tracepoints David Howells
2020-11-20 15:12 ` [RFC PATCH 46/76] fscache: Display cache-specific data in /proc/fs/fscache/objects David Howells
2020-11-20 15:12 ` [RFC PATCH 47/76] fscache: Remove more obsolete stats David Howells
2020-11-20 15:12 ` [RFC PATCH 48/76] fscache: Always create /proc/fs/fscache/stats if configured David Howells
2020-11-20 15:13 ` [RFC PATCH 49/76] netfs: Stats David Howells
2020-11-20 15:13 ` [RFC PATCH 50/76] fscache: New stats David Howells
2020-11-20 15:13 ` [RFC PATCH 51/76] fscache, cachefiles: Rewrite invalidation David Howells
2020-11-20 15:13 ` [RFC PATCH 52/76] fscache: disable cookie when doing an invalidation for DIO write David Howells
2020-11-20 15:13 ` [RFC PATCH 53/76] fscache: Implement "will_modify" parameter on fscache_use_cookie() David Howells
2020-11-20 15:14 ` [RFC PATCH 54/76] fscache: Provide resize operation David Howells
2020-11-20 15:14 ` [RFC PATCH 55/76] fscache: Remove the update operation David Howells
2020-11-20 15:14 ` [RFC PATCH 56/76] afs: Pass page into dirty region helpers to provide THP size David Howells
2020-11-20 15:14 ` [RFC PATCH 57/76] afs: Print the operation debug_id when logging an unexpected data version David Howells
2020-11-20 15:14 ` [RFC PATCH 58/76] afs: Move key to afs_read struct David Howells
2020-11-20 15:15 ` [RFC PATCH 59/76] afs: Don't truncate iter during data fetch David Howells
2020-11-20 15:15 ` [RFC PATCH 60/76] afs: Log remote unmarshalling errors David Howells
2020-11-20 15:15 ` [RFC PATCH 61/76] afs: Set up the iov_iter before calling afs_extract_data() David Howells
2020-11-20 15:15 ` [RFC PATCH 62/76] afs: Use ITER_XARRAY for writing David Howells
2020-11-20 15:16 ` [RFC PATCH 63/76] afs: Wait on PG_fscache before modifying/releasing a page David Howells
2020-11-20 15:16 ` [RFC PATCH 64/76] afs: Extract writeback extension into its own function David Howells
2020-11-20 15:16 ` [RFC PATCH 65/76] afs: Prepare for use of THPs David Howells
2020-11-20 15:16 ` [RFC PATCH 66/76] afs: Use the fs operation ops to handle FetchData completion David Howells
2020-11-20 15:17 ` [RFC PATCH 67/76] afs: Use new fscache read helper API David Howells
2020-11-20 15:17 ` [RFC PATCH 68/76] netfs: Add write_begin helper David Howells
2020-11-20 15:17 ` David Howells [this message]
2020-11-20 15:17 ` [RFC PATCH 70/76] afs: Use the fscache_write_begin() helper David Howells
2020-11-20 15:18 ` [RFC PATCH 71/76] afs: Copy local writes to the cache when writing to the server David Howells
2020-11-20 15:18 ` [RFC PATCH 72/76] afs: Invoke fscache_resize_cookie() when handling ATTR_SIZE for setattr David Howells
2020-11-20 15:18 ` [RFC PATCH 73/76] afs: Add O_DIRECT read support David Howells
2020-11-20 15:18 ` [RFC PATCH 74/76] afs: Skip truncation on the server of data we haven't written yet David Howells
2020-11-20 15:19 ` [RFC PATCH 75/76] afs: Make afs_write_begin() return the THP subpage David Howells
2020-11-20 15:19 ` [RFC PATCH 76/76] afs: Fix speculative status fetch going out of order wrt to modifications David Howells
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