All methods except prepare_read() of netfs_cache_ops works without
netfs_io_request/netfs_io_subrequest, which accept netfs_cache_resources
and a file range to be handled.

As fscache is now also used for local fs (e.g. erofs) in on-demand read
scenarios, we'd better make raw fscache APIs more neutral independent on
libnetfs.  Thus decouple prepare_read() from netfs_io_subrequest, just
like other methods do.

This is a cleanup without logic change, except that some debug info
retrieved from netfs_io_subrequest is removed from
trace_cachefiles_prep_read().

Signed-off-by: Jingbo Xu <jeffl...@linux.alibaba.com>
---
 fs/cachefiles/io.c                | 46 ++++++++++++++++---------------
 fs/erofs/fscache.c                |  3 +-
 fs/netfs/io.c                     |  3 +-
 include/linux/netfs.h             |  5 ++--
 include/trace/events/cachefiles.h | 23 ++++++----------
 5 files changed, 40 insertions(+), 40 deletions(-)

diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index 000a28f46e59..d5b6a2a75161 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -389,34 +389,35 @@ static int cachefiles_write(struct netfs_cache_resources 
*cres,
  * Prepare a read operation, shortening it to a cached/uncached
  * boundary as appropriate.
  */
-static enum netfs_io_source cachefiles_prepare_read(struct netfs_io_subrequest 
*subreq,
-                                                     loff_t i_size)
+static enum netfs_io_source cachefiles_prepare_read(struct 
netfs_cache_resources *cres,
+                                       loff_t *_start, size_t *_len,
+                                       unsigned long *_flags, loff_t i_size)
 {
        enum cachefiles_prepare_read_trace why;
-       struct netfs_io_request *rreq = subreq->rreq;
-       struct netfs_cache_resources *cres = &rreq->cache_resources;
        struct cachefiles_object *object;
        struct cachefiles_cache *cache;
        struct fscache_cookie *cookie = fscache_cres_cookie(cres);
        const struct cred *saved_cred;
        struct file *file = cachefiles_cres_file(cres);
        enum netfs_io_source ret = NETFS_DOWNLOAD_FROM_SERVER;
+       loff_t start = *_start;
+       size_t len = *_len;
        loff_t off, to;
        ino_t ino = file ? file_inode(file)->i_ino : 0;
        int rc;
 
-       _enter("%zx @%llx/%llx", subreq->len, subreq->start, i_size);
+       _enter("%zx @%llx/%llx", len, start, i_size);
 
-       if (subreq->start >= i_size) {
+       if (start >= i_size) {
                ret = NETFS_FILL_WITH_ZEROES;
                why = cachefiles_trace_read_after_eof;
                goto out_no_object;
        }
 
        if (test_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags)) {
-               __set_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags);
+               __set_bit(NETFS_SREQ_COPY_TO_CACHE, _flags);
                why = cachefiles_trace_read_no_data;
-               if (!test_bit(NETFS_SREQ_ONDEMAND, &subreq->flags))
+               if (!test_bit(NETFS_SREQ_ONDEMAND, _flags))
                        goto out_no_object;
        }
 
@@ -437,7 +438,7 @@ static enum netfs_io_source cachefiles_prepare_read(struct 
netfs_io_subrequest *
 retry:
        off = cachefiles_inject_read_error();
        if (off == 0)
-               off = vfs_llseek(file, subreq->start, SEEK_DATA);
+               off = vfs_llseek(file, start, SEEK_DATA);
        if (off < 0 && off >= (loff_t)-MAX_ERRNO) {
                if (off == (loff_t)-ENXIO) {
                        why = cachefiles_trace_read_seek_nxio;
@@ -449,21 +450,22 @@ static enum netfs_io_source 
cachefiles_prepare_read(struct netfs_io_subrequest *
                goto out;
        }
 
-       if (off >= subreq->start + subreq->len) {
+       if (off >= start + len) {
                why = cachefiles_trace_read_found_hole;
                goto download_and_store;
        }
 
-       if (off > subreq->start) {
+       if (off > start) {
                off = round_up(off, cache->bsize);
-               subreq->len = off - subreq->start;
+               len = off - start;
+               *_len = len;
                why = cachefiles_trace_read_found_part;
                goto download_and_store;
        }
 
        to = cachefiles_inject_read_error();
        if (to == 0)
-               to = vfs_llseek(file, subreq->start, SEEK_HOLE);
+               to = vfs_llseek(file, start, SEEK_HOLE);
        if (to < 0 && to >= (loff_t)-MAX_ERRNO) {
                trace_cachefiles_io_error(object, file_inode(file), to,
                                          cachefiles_trace_seek_error);
@@ -471,12 +473,13 @@ static enum netfs_io_source 
cachefiles_prepare_read(struct netfs_io_subrequest *
                goto out;
        }
 
-       if (to < subreq->start + subreq->len) {
-               if (subreq->start + subreq->len >= i_size)
+       if (to < start + len) {
+               if (start + len >= i_size)
                        to = round_up(to, cache->bsize);
                else
                        to = round_down(to, cache->bsize);
-               subreq->len = to - subreq->start;
+               len = to - start;
+               *_len = len;
        }
 
        why = cachefiles_trace_read_have_data;
@@ -484,12 +487,11 @@ static enum netfs_io_source 
cachefiles_prepare_read(struct netfs_io_subrequest *
        goto out;
 
 download_and_store:
-       __set_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags);
-       if (test_bit(NETFS_SREQ_ONDEMAND, &subreq->flags)) {
-               rc = cachefiles_ondemand_read(object, subreq->start,
-                                             subreq->len);
+       __set_bit(NETFS_SREQ_COPY_TO_CACHE, _flags);
+       if (test_bit(NETFS_SREQ_ONDEMAND, _flags)) {
+               rc = cachefiles_ondemand_read(object, start, len);
                if (!rc) {
-                       __clear_bit(NETFS_SREQ_ONDEMAND, &subreq->flags);
+                       __clear_bit(NETFS_SREQ_ONDEMAND, _flags);
                        goto retry;
                }
                ret = NETFS_INVALID_READ;
@@ -497,7 +499,7 @@ static enum netfs_io_source cachefiles_prepare_read(struct 
netfs_io_subrequest *
 out:
        cachefiles_end_secure(cache, saved_cred);
 out_no_object:
-       trace_cachefiles_prep_read(subreq, ret, why, ino);
+       trace_cachefiles_prep_read(start, len, *_flags, ret, why, ino);
        return ret;
 }
 
diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index fe05bc51f9f2..a4013f9bdb5c 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -176,7 +176,8 @@ static int erofs_fscache_read_folios_async(struct 
fscache_cookie *cookie,
 
                list_add_tail(&subreq->rreq_link, &rreq->subrequests);
 
-               source = cres->ops->prepare_read(subreq, LLONG_MAX);
+               source = cres->ops->prepare_read(cres, &subreq->start,
+                               &subreq->len, &subreq->flags, LLONG_MAX);
                if (WARN_ON(subreq->len == 0))
                        source = NETFS_INVALID_READ;
                if (source != NETFS_READ_FROM_CACHE) {
diff --git a/fs/netfs/io.c b/fs/netfs/io.c
index 428925899282..297423220fb1 100644
--- a/fs/netfs/io.c
+++ b/fs/netfs/io.c
@@ -487,7 +487,8 @@ static enum netfs_io_source netfs_cache_prepare_read(struct 
netfs_io_subrequest
        struct netfs_cache_resources *cres = &rreq->cache_resources;
 
        if (cres->ops)
-               return cres->ops->prepare_read(subreq, i_size);
+               return cres->ops->prepare_read(cres, &subreq->start,
+                               &subreq->len, &subreq->flags, i_size);
        if (subreq->start >= rreq->i_size)
                return NETFS_FILL_WITH_ZEROES;
        return NETFS_DOWNLOAD_FROM_SERVER;
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index f2402ddeafbf..b8171b3b9e2d 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -257,8 +257,9 @@ struct netfs_cache_ops {
        /* Prepare a read operation, shortening it to a cached/uncached
         * boundary as appropriate.
         */
-       enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq,
-                                            loff_t i_size);
+       enum netfs_io_source (*prepare_read)(struct netfs_cache_resources *cres,
+                                            loff_t *_start, size_t *_len,
+                                            unsigned long *_flags, loff_t 
i_size);
 
        /* Prepare a write operation, working out what part of the write we can
         * actually do.
diff --git a/include/trace/events/cachefiles.h 
b/include/trace/events/cachefiles.h
index d8d4d73fe7b6..62da0596f65b 100644
--- a/include/trace/events/cachefiles.h
+++ b/include/trace/events/cachefiles.h
@@ -428,44 +428,39 @@ TRACE_EVENT(cachefiles_vol_coherency,
            );
 
 TRACE_EVENT(cachefiles_prep_read,
-           TP_PROTO(struct netfs_io_subrequest *sreq,
+           TP_PROTO(loff_t start,
+                    size_t len,
+                    unsigned short flags,
                     enum netfs_io_source source,
                     enum cachefiles_prepare_read_trace why,
                     ino_t cache_inode),
 
-           TP_ARGS(sreq, source, why, cache_inode),
+           TP_ARGS(start, len, flags, source, why, cache_inode),
 
            TP_STRUCT__entry(
-                   __field(unsigned int,               rreq            )
-                   __field(unsigned short,             index           )
                    __field(unsigned short,             flags           )
                    __field(enum netfs_io_source,       source          )
                    __field(enum cachefiles_prepare_read_trace, why     )
                    __field(size_t,                     len             )
                    __field(loff_t,                     start           )
-                   __field(unsigned int,               netfs_inode     )
                    __field(unsigned int,               cache_inode     )
                             ),
 
            TP_fast_assign(
-                   __entry->rreq       = sreq->rreq->debug_id;
-                   __entry->index      = sreq->debug_index;
-                   __entry->flags      = sreq->flags;
+                   __entry->flags      = flags;
                    __entry->source     = source;
                    __entry->why        = why;
-                   __entry->len        = sreq->len;
-                   __entry->start      = sreq->start;
-                   __entry->netfs_inode = sreq->rreq->inode->i_ino;
+                   __entry->len        = len;
+                   __entry->start      = start;
                    __entry->cache_inode = cache_inode;
                           ),
 
-           TP_printk("R=%08x[%u] %s %s f=%02x s=%llx %zx ni=%x B=%x",
-                     __entry->rreq, __entry->index,
+           TP_printk("%s %s f=%02x s=%llx %zx B=%x",
                      __print_symbolic(__entry->source, netfs_sreq_sources),
                      __print_symbolic(__entry->why, 
cachefiles_prepare_read_traces),
                      __entry->flags,
                      __entry->start, __entry->len,
-                     __entry->netfs_inode, __entry->cache_inode)
+                     __entry->cache_inode)
            );
 
 TRACE_EVENT(cachefiles_read,
-- 
2.19.1.6.gb485710b

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