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@xxxxxxxxxx> cc: linux-cachefs@xxxxxxxxxx Link: https://lore.kernel.org/r/163819621839.215744.7895597119803515402.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v1 --- 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 1308bfff94fb..87884f4b34fb 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 fed7def0fbe0..b38d233c9fad 100644 --- a/include/linux/fscache.h +++ b/include/linux/fscache.h @@ -162,6 +162,7 @@ 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 *); @@ -362,6 +363,23 @@ 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 */
