Unverified Commit a41168ae authored by David Howells's avatar David Howells Committed by Christian Brauner
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netfs: Fix read-gaps to remove netfs_folio from filled folio 



Fix netfs_read_gaps() to remove the netfs_folio record from the folio
record before marking the folio uptodate if it successfully fills the gaps
around the dirty data in a streaming write folio (dirty, but not uptodate).

Found with:

    fsx -q -N 1000000 -p 10000 -o 128000 -l 600000 \
        /xfstest.test/junk --replay-ops=junk.fsxops

using the following as junk.fsxops:

    truncate 0x0 0x138b1 0x8b15d *
    write 0x507ee 0x10df7 0x927c0
    write 0x19993 0x10e04 0x927c0 *
    mapwrite 0x66214 0x1a253 0x927c0
    copy_range 0xb704 0x89b9 0x24429 0x79380
    write 0x2402b 0x144a2 0x90660 *
    mapwrite 0x204d5 0x140a0 0x927c0 *
    copy_range 0x1f72c 0x137d0 0x7a906 0x927c0 *
    read 0 0x9157c 0x9157c

on cifs with the default cache option.

It shows folio 0x24 misbehaving if the FMODE_READ check is commented out in
netfs_perform_write():

                if (//(file->f_mode & FMODE_READ) ||
                    netfs_is_cache_enabled(ctx)) {

and no fscache.  This was initially found with the generic/522 xfstest.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-16-dhowells@redhat.com


Fixes: ee4cdf7b ("netfs: Speed up buffered reading")
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent b6a4ae16

fs/netfs/buffered_read.c

+8 −3
Original line number Diff line number Diff line
@@ -395,6 +395,7 @@ static int netfs_read_gaps(struct file *file, struct folio *folio) 
{

	struct netfs_io_request *rreq;

	struct address_space *mapping = folio->mapping;

	struct netfs_group *group = netfs_folio_group(folio);

	struct netfs_folio *finfo = netfs_folio_info(folio);

	struct netfs_inode *ctx = netfs_inode(mapping->host);

	struct folio *sink = NULL;
@@ -461,6 +462,12 @@ static int netfs_read_gaps(struct file *file, struct folio *folio) 


	ret = netfs_wait_for_read(rreq);

	if (ret >= 0) {

		if (group)

			folio_change_private(folio, group);

		else

			folio_detach_private(folio);

		kfree(finfo);

		trace_netfs_folio(folio, netfs_folio_trace_filled_gaps);

		flush_dcache_folio(folio);

		folio_mark_uptodate(folio);

	}
@@ -496,10 +503,8 @@ int netfs_read_folio(struct file *file, struct folio *folio) 
	struct netfs_inode *ctx = netfs_inode(mapping->host);

	int ret;



	if (folio_test_dirty(folio)) {

		trace_netfs_folio(folio, netfs_folio_trace_read_gaps);

	if (folio_test_dirty(folio))

		return netfs_read_gaps(file, folio);

	}



	_enter("%lx", folio->index);