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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-06 19:07:52 +00:00
iomap: add the new iomap_iter model
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 <willy@infradead.org>. Signed-off-by: Christoph Hellwig <hch@lst.de> [djwong: add to apply.c to preserve git history of iomap loop control] Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com>
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parent
740499c784
commit
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3 changed files with 165 additions and 2 deletions
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@ -1,7 +1,7 @@
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// SPDX-License-Identifier: GPL-2.0
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// SPDX-License-Identifier: GPL-2.0
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/*
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/*
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* Copyright (C) 2010 Red Hat, Inc.
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* Copyright (C) 2010 Red Hat, Inc.
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* Copyright (c) 2016-2018 Christoph Hellwig.
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* Copyright (c) 2016-2021 Christoph Hellwig.
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*/
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*/
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#include <linux/module.h>
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#include <linux/module.h>
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#include <linux/compiler.h>
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#include <linux/compiler.h>
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@ -97,3 +97,75 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
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return written ? written : ret;
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return written ? written : ret;
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}
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}
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static inline int iomap_iter_advance(struct iomap_iter *iter)
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{
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/* handle the previous iteration (if any) */
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if (iter->iomap.length) {
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if (iter->processed <= 0)
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return iter->processed;
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if (WARN_ON_ONCE(iter->processed > iomap_length(iter)))
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return -EIO;
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iter->pos += iter->processed;
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iter->len -= iter->processed;
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if (!iter->len)
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return 0;
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}
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/* clear the state for the next iteration */
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iter->processed = 0;
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memset(&iter->iomap, 0, sizeof(iter->iomap));
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memset(&iter->srcmap, 0, sizeof(iter->srcmap));
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return 1;
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}
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static inline void iomap_iter_done(struct iomap_iter *iter)
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{
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WARN_ON_ONCE(iter->iomap.offset > iter->pos);
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WARN_ON_ONCE(iter->iomap.length == 0);
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WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos);
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trace_iomap_iter_dstmap(iter->inode, &iter->iomap);
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if (iter->srcmap.type != IOMAP_HOLE)
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trace_iomap_iter_srcmap(iter->inode, &iter->srcmap);
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}
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/**
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* iomap_iter - iterate over a ranges in a file
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* @iter: iteration structue
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* @ops: iomap ops provided by the file system
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*
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* Iterate over filesystem-provided space mappings for the provided file range.
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*
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* This function handles cleanup of resources acquired for iteration when the
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* filesystem indicates there are no more space mappings, which means that this
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* function must be called in a loop that continues as long it returns a
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* positive value. If 0 or a negative value is returned, the caller must not
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* return to the loop body. Within a loop body, there are two ways to break out
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* of the loop body: leave @iter.processed unchanged, or set it to a negative
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* errno.
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*/
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int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
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{
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int ret;
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if (iter->iomap.length && ops->iomap_end) {
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ret = ops->iomap_end(iter->inode, iter->pos, iomap_length(iter),
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iter->processed > 0 ? iter->processed : 0,
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iter->flags, &iter->iomap);
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if (ret < 0 && !iter->processed)
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return ret;
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}
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trace_iomap_iter(iter, ops, _RET_IP_);
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ret = iomap_iter_advance(iter);
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if (ret <= 0)
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return ret;
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ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,
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&iter->iomap, &iter->srcmap);
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if (ret < 0)
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return ret;
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iomap_iter_done(iter);
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return 1;
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}
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@ -1,6 +1,6 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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/*
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* Copyright (c) 2009-2019 Christoph Hellwig
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* Copyright (c) 2009-2021 Christoph Hellwig
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*
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*
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* NOTE: none of these tracepoints shall be considered a stable kernel ABI
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* NOTE: none of these tracepoints shall be considered a stable kernel ABI
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* as they can change at any time.
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* as they can change at any time.
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@ -140,6 +140,8 @@ DEFINE_EVENT(iomap_class, name, \
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TP_ARGS(inode, iomap))
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TP_ARGS(inode, iomap))
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DEFINE_IOMAP_EVENT(iomap_apply_dstmap);
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DEFINE_IOMAP_EVENT(iomap_apply_dstmap);
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DEFINE_IOMAP_EVENT(iomap_apply_srcmap);
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DEFINE_IOMAP_EVENT(iomap_apply_srcmap);
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DEFINE_IOMAP_EVENT(iomap_iter_dstmap);
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DEFINE_IOMAP_EVENT(iomap_iter_srcmap);
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TRACE_EVENT(iomap_apply,
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TRACE_EVENT(iomap_apply,
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TP_PROTO(struct inode *inode, loff_t pos, loff_t length,
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TP_PROTO(struct inode *inode, loff_t pos, loff_t length,
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@ -179,6 +181,39 @@ TRACE_EVENT(iomap_apply,
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__entry->actor)
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__entry->actor)
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);
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);
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TRACE_EVENT(iomap_iter,
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TP_PROTO(struct iomap_iter *iter, const void *ops,
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unsigned long caller),
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TP_ARGS(iter, ops, caller),
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TP_STRUCT__entry(
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__field(dev_t, dev)
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__field(u64, ino)
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__field(loff_t, pos)
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__field(loff_t, length)
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__field(unsigned int, flags)
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__field(const void *, ops)
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__field(unsigned long, caller)
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),
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TP_fast_assign(
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__entry->dev = iter->inode->i_sb->s_dev;
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__entry->ino = iter->inode->i_ino;
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__entry->pos = iter->pos;
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__entry->length = iomap_length(iter);
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__entry->flags = iter->flags;
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__entry->ops = ops;
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__entry->caller = caller;
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),
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TP_printk("dev %d:%d ino 0x%llx pos %lld length %lld flags %s (0x%x) ops %ps caller %pS",
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MAJOR(__entry->dev), MINOR(__entry->dev),
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__entry->ino,
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__entry->pos,
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__entry->length,
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__print_flags(__entry->flags, "|", IOMAP_FLAGS_STRINGS),
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__entry->flags,
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__entry->ops,
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(void *)__entry->caller)
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);
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#endif /* _IOMAP_TRACE_H */
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#endif /* _IOMAP_TRACE_H */
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#undef TRACE_INCLUDE_PATH
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#undef TRACE_INCLUDE_PATH
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@ -161,6 +161,62 @@ struct iomap_ops {
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ssize_t written, unsigned flags, struct iomap *iomap);
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ssize_t written, unsigned flags, struct iomap *iomap);
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};
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};
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/**
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* struct iomap_iter - Iterate through a range of a file
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* @inode: Set at the start of the iteration and should not change.
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* @pos: The current file position we are operating on. It is updated by
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* calls to iomap_iter(). Treat as read-only in the body.
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* @len: The remaining length of the file segment we're operating on.
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* It is updated at the same time as @pos.
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* @processed: The number of bytes processed by the body in the most recent
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* iteration, or a negative errno. 0 causes the iteration to stop.
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* @flags: Zero or more of the iomap_begin flags above.
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* @iomap: Map describing the I/O iteration
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* @srcmap: Source map for COW operations
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*/
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struct iomap_iter {
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struct inode *inode;
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loff_t pos;
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u64 len;
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s64 processed;
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unsigned flags;
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struct iomap iomap;
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struct iomap srcmap;
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};
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int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops);
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/**
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* iomap_length - length of the current iomap iteration
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* @iter: iteration structure
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*
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* Returns the length that the operation applies to for the current iteration.
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*/
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static inline u64 iomap_length(const struct iomap_iter *iter)
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{
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u64 end = iter->iomap.offset + iter->iomap.length;
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if (iter->srcmap.type != IOMAP_HOLE)
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end = min(end, iter->srcmap.offset + iter->srcmap.length);
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return min(iter->len, end - iter->pos);
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}
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/**
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* iomap_iter_srcmap - return the source map for the current iomap iteration
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* @i: iteration structure
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*
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* Write operations on file systems with reflink support might require a
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* source and a destination map. This function retourns the source map
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* for a given operation, which may or may no be identical to the destination
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* map in &i->iomap.
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*/
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static inline struct iomap *iomap_iter_srcmap(struct iomap_iter *i)
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{
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if (i->srcmap.type != IOMAP_HOLE)
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return &i->srcmap;
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return &i->iomap;
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}
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/*
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/*
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* Main iomap iterator function.
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* Main iomap iterator function.
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*/
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*/
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