From patchwork Mon Jul 19 10:35:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 12385301 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0CDFB2FB0 for ; Mon, 19 Jul 2021 10:46:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=mwtTfl/Vfd2ADz2AOMzpPzOaKKWgkXM4Svr1jS/ya70=; b=gxYF7iS6ofZTT56YA3tacKYq/a YZZjqNyqNo/xfkbzt3VULB6iy6/DpnkSof1uQ5UDgKGfTJnlFORblqN2pNj9GFtdQl/OcsxFsRu7x D3FegsEXiz6Fpmd2/HfXmPWcR8UQpwc5P+Wv797YQnaG1GHpOyRZrlz9hT1C9ZDv/zujGwGdpACQo u7oltUHmFS5hwmKTzCx+XC7dvOUqRWbQrH+2AVVhUM9u/t1tN74HHiXacPT/Dp0x3r9WWhdk19cVN bW5/2N9POgkkvhuVSkdEsX8eq9nEep/+oPtvDwhZSnR5sEz96HO+I2u6kgy1gXdDE7dpYjIfRhmCP UNwMBqqw==; Received: from [2001:4bb8:193:7660:d2a4:8d57:2e55:21d0] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1m5QjN-006kuz-0s; Mon, 19 Jul 2021 10:42:59 +0000 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Dan Williams , Matthew Wilcox , Andreas Gruenbacher , Shiyang Ruan , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, nvdimm@lists.linux.dev, cluster-devel@redhat.com Subject: [PATCH 08/27] iomap: add the new iomap_iter model Date: Mon, 19 Jul 2021 12:35:01 +0200 Message-Id: <20210719103520.495450-9-hch@lst.de> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210719103520.495450-1-hch@lst.de> References: <20210719103520.495450-1-hch@lst.de> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html The iomap_iter struct provides a convenient way to package up and maintain all the arguments to the various mapping and operation functions. It is operated on using the iomap_iter() function that is called in loop until the whole range has been processed. Compared to the existing iomap_apply() function this avoid an indirect call for each iteration. For now iomap_iter() calls back into the existing ->iomap_begin and ->iomap_end methods, but in the future this could be further optimized to avoid indirect calls entirely. Based on an earlier patch from Matthew Wilcox . Signed-off-by: Christoph Hellwig --- fs/iomap/Makefile | 1 + fs/iomap/iter.c | 74 +++++++++++++++++++++++++++++++++++++++++++ fs/iomap/trace.h | 37 +++++++++++++++++++++- include/linux/iomap.h | 56 ++++++++++++++++++++++++++++++++ 4 files changed, 167 insertions(+), 1 deletion(-) create mode 100644 fs/iomap/iter.c diff --git a/fs/iomap/Makefile b/fs/iomap/Makefile index eef2722d93a183..85034deb5a2f19 100644 --- a/fs/iomap/Makefile +++ b/fs/iomap/Makefile @@ -10,6 +10,7 @@ obj-$(CONFIG_FS_IOMAP) += iomap.o iomap-y += trace.o \ apply.o \ + iter.o \ buffered-io.o \ direct-io.o \ fiemap.o \ diff --git a/fs/iomap/iter.c b/fs/iomap/iter.c new file mode 100644 index 00000000000000..b21e2489700b7c --- /dev/null +++ b/fs/iomap/iter.c @@ -0,0 +1,74 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2021 Christoph Hellwig. + */ +#include +#include +#include "trace.h" + +static inline int iomap_iter_advance(struct iomap_iter *iter) +{ + /* handle the previous iteration (if any) */ + if (iter->iomap.length) { + if (iter->processed <= 0) + return iter->processed; + WARN_ON_ONCE(iter->processed > iomap_length(iter)); + iter->pos += iter->processed; + iter->len -= iter->processed; + if (!iter->len) + return 0; + } + + /* clear the state for the next iteration */ + iter->processed = 0; + memset(&iter->iomap, 0, sizeof(iter->iomap)); + memset(&iter->srcmap, 0, sizeof(iter->srcmap)); + return 1; +} + +static inline void iomap_iter_done(struct iomap_iter *iter) +{ + WARN_ON_ONCE(iter->iomap.offset > iter->pos); + WARN_ON_ONCE(iter->iomap.length == 0); + WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos); + + trace_iomap_iter_dstmap(iter->inode, &iter->iomap); + if (iter->srcmap.type != IOMAP_HOLE) + trace_iomap_iter_srcmap(iter->inode, &iter->srcmap); +} + +/** + * iomap_iter - iterate over a ranges in a file + * @iter: iteration structue + * @ops: iomap ops provided by the file system + * + * Iterate over file system provided contiguous ranges of blocks with the same + * state. Should be called in a loop that continues as long as this function + * returns a positive value. If 0 or a negative value is returned the caller + * should break out of the loop - a negative value is an error either from the + * file system or from the last iteration stored in @iter.copied. + */ +int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops) +{ + int ret; + + if (iter->iomap.length && ops->iomap_end) { + ret = ops->iomap_end(iter->inode, iter->pos, iomap_length(iter), + iter->processed > 0 ? iter->processed : 0, + iter->flags, &iter->iomap); + if (ret < 0 && !iter->processed) + return ret; + } + + trace_iomap_iter(iter, ops, _RET_IP_); + ret = iomap_iter_advance(iter); + if (ret <= 0) + return ret; + + ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags, + &iter->iomap, &iter->srcmap); + if (ret < 0) + return ret; + iomap_iter_done(iter); + return 1; +} diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h index e9cd5cc0d6ba40..1012d7af6b689b 100644 --- a/fs/iomap/trace.h +++ b/fs/iomap/trace.h @@ -1,6 +1,6 @@ /* SPDX-License-Identifier: GPL-2.0 */ /* - * Copyright (c) 2009-2019 Christoph Hellwig + * Copyright (c) 2009-2021 Christoph Hellwig * * NOTE: none of these tracepoints shall be considered a stable kernel ABI * as they can change at any time. @@ -140,6 +140,8 @@ DEFINE_EVENT(iomap_class, name, \ TP_ARGS(inode, iomap)) DEFINE_IOMAP_EVENT(iomap_apply_dstmap); DEFINE_IOMAP_EVENT(iomap_apply_srcmap); +DEFINE_IOMAP_EVENT(iomap_iter_dstmap); +DEFINE_IOMAP_EVENT(iomap_iter_srcmap); TRACE_EVENT(iomap_apply, TP_PROTO(struct inode *inode, loff_t pos, loff_t length, @@ -179,6 +181,39 @@ TRACE_EVENT(iomap_apply, __entry->actor) ); +TRACE_EVENT(iomap_iter, + TP_PROTO(struct iomap_iter *iter, const void *ops, + unsigned long caller), + TP_ARGS(iter, ops, caller), + TP_STRUCT__entry( + __field(dev_t, dev) + __field(u64, ino) + __field(loff_t, pos) + __field(loff_t, length) + __field(unsigned int, flags) + __field(const void *, ops) + __field(unsigned long, caller) + ), + TP_fast_assign( + __entry->dev = iter->inode->i_sb->s_dev; + __entry->ino = iter->inode->i_ino; + __entry->pos = iter->pos; + __entry->length = iomap_length(iter); + __entry->flags = iter->flags; + __entry->ops = ops; + __entry->caller = caller; + ), + TP_printk("dev %d:%d ino 0x%llx pos %lld length %lld flags %s (0x%x) ops %ps caller %pS", + MAJOR(__entry->dev), MINOR(__entry->dev), + __entry->ino, + __entry->pos, + __entry->length, + __print_flags(__entry->flags, "|", IOMAP_FLAGS_STRINGS), + __entry->flags, + __entry->ops, + (void *)__entry->caller) +); + #endif /* _IOMAP_TRACE_H */ #undef TRACE_INCLUDE_PATH diff --git a/include/linux/iomap.h b/include/linux/iomap.h index f9c36df6a3061b..a9f3f736017989 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -143,6 +143,62 @@ struct iomap_ops { ssize_t written, unsigned flags, struct iomap *iomap); }; +/** + * struct iomap_iter - Iterate through a range of a file + * @inode: Set at the start of the iteration and should not change. + * @pos: The current file position we are operating on. It is updated by + * calls to iomap_iter(). Treat as read-only in the body. + * @len: The remaining length of the file segment we're operating on. + * It is updated at the same time as @pos. + * @processed: The number of bytes processed by the body in the most recent + * iteration, or a negative errno. 0 causes the iteration to stop. + * @flags: Zero or more of the iomap_begin flags above. + * @iomap: Map describing the I/O iteration + * @srcmap: Source map for COW operations + */ +struct iomap_iter { + struct inode *inode; + loff_t pos; + u64 len; + ssize_t processed; + unsigned flags; + struct iomap iomap; + struct iomap srcmap; +}; + +int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops); + +/** + * iomap_length - length of the current iomap iteration + * @iter: iteration structure + * + * Returns the length that the operation applies to for the current iteration. + */ +static inline u64 iomap_length(const struct iomap_iter *iter) +{ + u64 end = iter->iomap.offset + iter->iomap.length; + + if (iter->srcmap.type != IOMAP_HOLE) + end = min(end, iter->srcmap.offset + iter->srcmap.length); + return min(iter->len, end - iter->pos); +} + +/** + * iomap_iter_srcmap - return the source map for the current iomap iteration + * @i: iteration structure + * + * Write operations on file systems with reflink support might require a + * source and a destination map. This function retourns the source map + * for a given operation, which may or may no be identical to the destination + * map in &i->iomap. + */ +static inline struct iomap *iomap_iter_srcmap(struct iomap_iter *i) +{ + if (i->srcmap.type != IOMAP_HOLE) + return &i->srcmap; + return &i->iomap; +} + /* * Main iomap iterator function. */