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afs: Stop implementing ->writepage() 

We're trying to get rid of the ->writepage() hook[1].  Stop afs from using
it by unlocking the page and calling afs_writepages_region() rather than
folio_write_one().

A flag is passed to afs_writepages_region() to indicate that it should only
write a single region so that we don't flush the entire file in
->write_begin(), but do add other dirty data to the region being written to
try and reduce the number of RPC ops.

This requires ->migrate_folio() to be implemented, so point that at
filemap_migrate_folio() for files and also for symlinks and directories.

This can be tested by turning on the afs_folio_dirty tracepoint and then
doing something like:

   xfs_io -c "w 2223 7000" -c "w 15000 22222" -c "w 23 7" /afs/my/test/foo

and then looking in the trace to see if the write at position 15000 gets
stored before page 0 gets dirtied for the write at position 23.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Christoph Hellwig <hch@lst.de>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/20221113162902.883850-1-hch@lst.de/ [1]
Link: https://lore.kernel.org/r/166876785552.222254.4403222906022558715.stgit@warthog.procyon.org.uk/ # v1
This commit is contained in:
David Howells 2022-11-18 07:57:27 +00:00
parent b3d3ca5567
commit a9eb558a5b
3 changed files with 50 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
fs/afs/dir.c
View File

@ -77,6 +77,7 @@ const struct address_space_operations afs_dir_aops = {
.dirty_folio = afs_dir_dirty_folio,
.release_folio = afs_dir_release_folio,
.invalidate_folio = afs_dir_invalidate_folio,
.migrate_folio = filemap_migrate_folio,
};
const struct dentry_operations afs_fs_dentry_operations = {

3
fs/afs/file.c
View File

@ -58,14 +58,15 @@ const struct address_space_operations afs_file_aops = {
.invalidate_folio = afs_invalidate_folio,
.write_begin = afs_write_begin,
.write_end = afs_write_end,
.writepage = afs_writepage,
.writepages = afs_writepages,
.migrate_folio = filemap_migrate_folio,
};
const struct address_space_operations afs_symlink_aops = {
.read_folio = afs_symlink_read_folio,
.release_folio = afs_release_folio,
.invalidate_folio = afs_invalidate_folio,
.migrate_folio = filemap_migrate_folio,
};
static const struct vm_operations_struct afs_vm_ops = {

83
fs/afs/write.c
View File

@ -14,6 +14,11 @@
#include <linux/netfs.h>
#include "internal.h"
static int afs_writepages_region(struct address_space *mapping,
struct writeback_control *wbc,
loff_t start, loff_t end, loff_t *_next,
bool max_one_loop);
static void afs_write_to_cache(struct afs_vnode *vnode, loff_t start, size_t len,
loff_t i_size, bool caching);
@ -38,6 +43,25 @@ static void afs_folio_start_fscache(bool caching, struct folio *folio)
}
#endif
/*
* Flush out a conflicting write. This may extend the write to the surrounding
* pages if also dirty and contiguous to the conflicting region..
*/
static int afs_flush_conflicting_write(struct address_space *mapping,
struct folio *folio)
{
struct writeback_control wbc = {
.sync_mode = WB_SYNC_ALL,
.nr_to_write = LONG_MAX,
.range_start = folio_pos(folio),
.range_end = LLONG_MAX,
};
loff_t next;
return afs_writepages_region(mapping, &wbc, folio_pos(folio), LLONG_MAX,
&next, true);
}
/*
* prepare to perform part of a write to a page
*/
@ -80,7 +104,8 @@ try_again:
if (folio_test_writeback(folio)) {
trace_afs_folio_dirty(vnode, tracepoint_string("alrdy"), folio);
goto flush_conflicting_write;
folio_unlock(folio);
goto wait_for_writeback;
}
/* If the file is being filled locally, allow inter-write
* spaces to be merged into writes. If it's not, only write
@ -99,8 +124,15 @@ try_again:
* flush the page out.
*/
flush_conflicting_write:
_debug("flush conflict");
ret = folio_write_one(folio);
trace_afs_folio_dirty(vnode, tracepoint_string("confl"), folio);
folio_unlock(folio);
ret = afs_flush_conflicting_write(mapping, folio);
if (ret < 0)
goto error;
wait_for_writeback:
ret = folio_wait_writeback_killable(folio);
if (ret < 0)
goto error;
@ -663,40 +695,13 @@ static ssize_t afs_write_back_from_locked_folio(struct address_space *mapping,
return ret;
}
/*
* write a page back to the server
* - the caller locked the page for us
*/
int afs_writepage(struct page *subpage, struct writeback_control *wbc)
{
struct folio *folio = page_folio(subpage);
ssize_t ret;
loff_t start;
_enter("{%lx},", folio_index(folio));
#ifdef CONFIG_AFS_FSCACHE
folio_wait_fscache(folio);
#endif
start = folio_index(folio) * PAGE_SIZE;
ret = afs_write_back_from_locked_folio(folio_mapping(folio), wbc,
folio, start, LLONG_MAX - start);
if (ret < 0) {
_leave(" = %zd", ret);
return ret;
}
_leave(" = 0");
return 0;
}
/*
* write a region of pages back to the server
*/
static int afs_writepages_region(struct address_space *mapping,
struct writeback_control *wbc,
loff_t start, loff_t end, loff_t *_next)
loff_t start, loff_t end, loff_t *_next,
bool max_one_loop)
{
struct folio *folio;
struct page *head_page;
@ -775,6 +780,9 @@ static int afs_writepages_region(struct address_space *mapping,
start += ret;
if (max_one_loop)
break;
cond_resched();
} while (wbc->nr_to_write > 0);
@ -806,24 +814,27 @@ int afs_writepages(struct address_space *mapping,
if (wbc->range_cyclic) {
start = mapping->writeback_index * PAGE_SIZE;
ret = afs_writepages_region(mapping, wbc, start, LLONG_MAX, &next);
ret = afs_writepages_region(mapping, wbc, start, LLONG_MAX,
&next, false);
if (ret == 0) {
mapping->writeback_index = next / PAGE_SIZE;
if (start > 0 && wbc->nr_to_write > 0) {
ret = afs_writepages_region(mapping, wbc, 0,
start, &next);
start, &next, false);
if (ret == 0)
mapping->writeback_index =
next / PAGE_SIZE;
}
}
} else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
ret = afs_writepages_region(mapping, wbc, 0, LLONG_MAX, &next);
ret = afs_writepages_region(mapping, wbc, 0, LLONG_MAX,
&next, false);
if (wbc->nr_to_write > 0 && ret == 0)
mapping->writeback_index = next / PAGE_SIZE;
} else {
ret = afs_writepages_region(mapping, wbc,
wbc->range_start, wbc->range_end, &next);
wbc->range_start, wbc->range_end,
&next, false);
}
up_read(&vnode->validate_lock);