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netfs: Add a function to consolidate beginning a read 

Add a function to do the steps needed to begin a read request, allowing
this code to be removed from several other functions and consolidated.

Changes
=======
ver #2)
 - Move before the unstaticking patch so that some functions can be left
   static.
 - Set uninitialised return code in netfs_begin_read()[1][2].
 - Fixed a refleak caused by non-removal of a get from netfs_write_begin()
   when the request submission code got moved to netfs_begin_read().
 - Use INIT_WORK() to (re-)init the request work_struct[3].

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/20220303163826.1120936-1-nathan@kernel.org/ [1]
Link: https://lore.kernel.org/r/20220303235647.1297171-1-colin.i.king@gmail.com/ [2]
Link: https://lore.kernel.org/r/9d69be49081bccff44260e4c6e0049c63d6d04a1.camel@redhat.com/ [3]
Link: https://lore.kernel.org/r/164623004355.3564931.7275693529042495641.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678214287.1200972.16734134007649832160.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692911113.2099075.1060868473229451371.stgit@warthog.procyon.org.uk/ # v3
This commit is contained in:
David Howells 2022-03-02 10:50:22 +00:00
parent bc899ee1c8
commit 4090b31422
4 changed files with 76 additions and 76 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/netfs/internal.h
View File

@ -39,7 +39,7 @@ static inline void netfs_see_request(struct netfs_io_request *rreq,
*/
extern unsigned int netfs_debug;
void netfs_rreq_work(struct work_struct *work);
int netfs_begin_read(struct netfs_io_request *rreq, bool sync);
/*
* stats.c

1
fs/netfs/objects.c
View File

@ -35,7 +35,6 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
rreq->i_size = i_size_read(inode);
rreq->debug_id = atomic_inc_return(&debug_ids);
INIT_LIST_HEAD(&rreq->subrequests);
INIT_WORK(&rreq->work, netfs_rreq_work);
refcount_set(&rreq->ref, 1);
__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
if (rreq->netfs_ops->init_request) {

144
fs/netfs/read_helper.c
View File

@ -443,7 +443,7 @@ again:
netfs_rreq_completed(rreq, was_async);
}
void netfs_rreq_work(struct work_struct *work)
static void netfs_rreq_work(struct work_struct *work)
{
struct netfs_io_request *rreq =
container_of(work, struct netfs_io_request, work);
@ -688,6 +688,69 @@ subreq_failed:
return false;
}
/*
* Begin the process of reading in a chunk of data, where that data may be
* stitched together from multiple sources, including multiple servers and the
* local cache.
*/
int netfs_begin_read(struct netfs_io_request *rreq, bool sync)
{
unsigned int debug_index = 0;
int ret;
_enter("R=%x %llx-%llx",
rreq->debug_id, rreq->start, rreq->start + rreq->len - 1);
if (rreq->len == 0) {
pr_err("Zero-sized read [R=%x]\n", rreq->debug_id);
netfs_put_request(rreq, false, netfs_rreq_trace_put_zero_len);
return -EIO;
}
INIT_WORK(&rreq->work, netfs_rreq_work);
if (sync)
netfs_get_request(rreq, netfs_rreq_trace_get_hold);
/* Chop the read into slices according to what the cache and the netfs
* want and submit each one.
*/
atomic_set(&rreq->nr_outstanding, 1);
do {
if (!netfs_rreq_submit_slice(rreq, &debug_index))
break;
} while (rreq->submitted < rreq->len);
if (sync) {
/* Keep nr_outstanding incremented so that the ref always belongs to
* us, and the service code isn't punted off to a random thread pool to
* process.
*/
for (;;) {
wait_var_event(&rreq->nr_outstanding,
atomic_read(&rreq->nr_outstanding) == 1);
netfs_rreq_assess(rreq, false);
if (!test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags))
break;
cond_resched();
}
ret = rreq->error;
if (ret == 0 && rreq->submitted < rreq->len) {
trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_read);
ret = -EIO;
}
netfs_put_request(rreq, false, netfs_rreq_trace_put_hold);
} else {
/* If we decrement nr_outstanding to 0, the ref belongs to us. */
if (atomic_dec_and_test(&rreq->nr_outstanding))
netfs_rreq_assess(rreq, false);
ret = 0;
}
return ret;
}
static void netfs_cache_expand_readahead(struct netfs_io_request *rreq,
loff_t *_start, size_t *_len, loff_t i_size)
{
@ -750,7 +813,6 @@ void netfs_readahead(struct readahead_control *ractl)
{
struct netfs_io_request *rreq;
struct netfs_i_context *ctx = netfs_i_context(ractl->mapping->host);
unsigned int debug_index = 0;
int ret;
_enter("%lx,%x", readahead_index(ractl), readahead_count(ractl));
@ -777,22 +839,13 @@ void netfs_readahead(struct readahead_control *ractl)
netfs_rreq_expand(rreq, ractl);
atomic_set(&rreq->nr_outstanding, 1);
do {
if (!netfs_rreq_submit_slice(rreq, &debug_index))
break;
} while (rreq->submitted < rreq->len);
/* Drop the refs on the folios here rather than in the cache or
* filesystem. The locks will be dropped in netfs_rreq_unlock().
*/
while (readahead_folio(ractl))
;
/* If we decrement nr_outstanding to 0, the ref belongs to us. */
if (atomic_dec_and_test(&rreq->nr_outstanding))
netfs_rreq_assess(rreq, false);
netfs_begin_read(rreq, false);
return;
cleanup_free:
@ -821,7 +874,6 @@ int netfs_readpage(struct file *file, struct page *subpage)
struct address_space *mapping = folio->mapping;
struct netfs_io_request *rreq;
struct netfs_i_context *ctx = netfs_i_context(mapping->host);
unsigned int debug_index = 0;
int ret;
_enter("%lx", folio_index(folio));
@ -836,42 +888,16 @@ int netfs_readpage(struct file *file, struct page *subpage)
if (ctx->ops->begin_cache_operation) {
ret = ctx->ops->begin_cache_operation(rreq);
if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS) {
folio_unlock(folio);
goto out;
}
if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
goto discard;
}
netfs_stat(&netfs_n_rh_readpage);
trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
return netfs_begin_read(rreq, true);
netfs_get_request(rreq, netfs_rreq_trace_get_hold);
atomic_set(&rreq->nr_outstanding, 1);
do {
if (!netfs_rreq_submit_slice(rreq, &debug_index))
break;
} while (rreq->submitted < rreq->len);
/* Keep nr_outstanding incremented so that the ref always belongs to us, and
* the service code isn't punted off to a random thread pool to
* process.
*/
do {
wait_var_event(&rreq->nr_outstanding,
atomic_read(&rreq->nr_outstanding) == 1);
netfs_rreq_assess(rreq, false);
} while (test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags));
ret = rreq->error;
if (ret == 0 && rreq->submitted < rreq->len) {
trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_readpage);
ret = -EIO;
}
out:
netfs_put_request(rreq, false, netfs_rreq_trace_put_hold);
return ret;
discard:
netfs_put_request(rreq, false, netfs_rreq_trace_put_discard);
alloc_error:
folio_unlock(folio);
return ret;
@ -966,7 +992,7 @@ int netfs_write_begin(struct file *file, struct address_space *mapping,
struct netfs_io_request *rreq;
struct netfs_i_context *ctx = netfs_i_context(file_inode(file ));
struct folio *folio;
unsigned int debug_index = 0, fgp_flags;
unsigned int fgp_flags;
pgoff_t index = pos >> PAGE_SHIFT;
int ret;
@ -1029,39 +1055,13 @@ retry:
*/
ractl._nr_pages = folio_nr_pages(folio);
netfs_rreq_expand(rreq, &ractl);
netfs_get_request(rreq, netfs_rreq_trace_get_hold);
/* We hold the folio locks, so we can drop the references */
folio_get(folio);
while (readahead_folio(&ractl))
;
atomic_set(&rreq->nr_outstanding, 1);
do {
if (!netfs_rreq_submit_slice(rreq, &debug_index))
break;
} while (rreq->submitted < rreq->len);
/* Keep nr_outstanding incremented so that the ref always belongs to
* us, and the service code isn't punted off to a random thread pool to
* process.
*/
for (;;) {
wait_var_event(&rreq->nr_outstanding,
atomic_read(&rreq->nr_outstanding) == 1);
netfs_rreq_assess(rreq, false);
if (!test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags))
break;
cond_resched();
}
ret = rreq->error;
if (ret == 0 && rreq->submitted < rreq->len) {
trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_write_begin);
ret = -EIO;
}
netfs_put_request(rreq, false, netfs_rreq_trace_put_hold);
ret = netfs_begin_read(rreq, true);
if (ret < 0)
goto error;

5
include/trace/events/netfs.h
View File

@ -56,17 +56,18 @@
EM(netfs_fail_check_write_begin, "check-write-begin") \
EM(netfs_fail_copy_to_cache, "copy-to-cache") \
EM(netfs_fail_read, "read") \
EM(netfs_fail_short_readpage, "short-readpage") \
EM(netfs_fail_short_write_begin, "short-write-begin") \
EM(netfs_fail_short_read, "short-read") \
E_(netfs_fail_prepare_write, "prep-write")
#define netfs_rreq_ref_traces \
EM(netfs_rreq_trace_get_hold, "GET HOLD ") \
EM(netfs_rreq_trace_get_subreq, "GET SUBREQ ") \
EM(netfs_rreq_trace_put_complete, "PUT COMPLT ") \
EM(netfs_rreq_trace_put_discard, "PUT DISCARD") \
EM(netfs_rreq_trace_put_failed, "PUT FAILED ") \
EM(netfs_rreq_trace_put_hold, "PUT HOLD ") \
EM(netfs_rreq_trace_put_subreq, "PUT SUBREQ ") \
EM(netfs_rreq_trace_put_zero_len, "PUT ZEROLEN") \
E_(netfs_rreq_trace_new, "NEW ")
#define netfs_sreq_ref_traces \