5.10-stable review patch. If anyone has any objections, please let me know.
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From: Christoph Hellwig hch@lst.de
[ Upstream commit f4b896c213f0752adc828ddc11bd55419ffab248 ]
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 Stable-dep-of: 154d1e7ad9e5 ("dax: skip read lock assertion for read-only filesystems") Signed-off-by: Sasha Levin sashal@kernel.org --- fs/iomap/apply.c | 74 ++++++++++++++++++++++++++++++++++++++++++- fs/iomap/trace.h | 37 +++++++++++++++++++++- include/linux/iomap.h | 56 ++++++++++++++++++++++++++++++++ 3 files changed, 165 insertions(+), 2 deletions(-)
diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c index 26ab6563181fc..e82647aef7ead 100644 --- a/fs/iomap/apply.c +++ b/fs/iomap/apply.c @@ -1,7 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2010 Red Hat, Inc. - * Copyright (c) 2016-2018 Christoph Hellwig. + * Copyright (c) 2016-2021 Christoph Hellwig. */ #include <linux/module.h> #include <linux/compiler.h> @@ -97,3 +97,75 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
return written ? written : ret; } + +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; + if (WARN_ON_ONCE(iter->processed > iomap_length(iter))) + return -EIO; + 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 filesystem-provided space mappings for the provided file range. + * + * This function handles cleanup of resources acquired for iteration when the + * filesystem indicates there are no more space mappings, which means that this + * function must be called in a loop that continues as long it returns a + * positive value. If 0 or a negative value is returned, the caller must not + * return to the loop body. Within a loop body, there are two ways to break out + * of the loop body: leave @iter.processed unchanged, or set it to a negative + * errno. + */ +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 fdc7ae388476f..52b850b4d3f44 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 consider 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 5bd3cac4df9cb..5100a139d2efd 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; + s64 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. */