kernel.git/fs/gfs2/aops.c, branch linux-5.12.y

gfs2: Fix case in which ail writes are done to jdata holes

2020-11-12T17:55:20Z

Patch b2a846dbef4e ("gfs2: Ignore journal log writes for jdata holes") tried (unsuccessfully) to fix a case in which writes were done to jdata blocks, the blocks are sent to the ail list, then a punch_hole or truncate operation caused the blocks to be freed. In other words, the ail items are for jdata holes. Before b2a846dbef4e, the jdata hole caused function gfs2_block_map to return -EIO, which was eventually interpreted as an IO error to the journal, and then withdraw. This patch changes function gfs2_get_block_noalloc, which is only used for jdata writes, so it returns -ENODATA rather than -EIO, and when -ENODATA is returned to gfs2_ail1_start_one, the error is ignored. We can safely ignore it because gfs2_ail1_start_one is only called when the jdata pages have already been written and truncated, so the ail1 content no longer applies. Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher

gfs2: Only set PageChecked if we have a transaction

2020-10-15T12:29:03Z

With jdata writes, we frequently got into situations where gfs2 deadlocked because of this calling sequence: gfs2_ail1_start gfs2_ail1_flush - for every tr on the sd_ail1_list: gfs2_ail1_start_one - for every bd on the tr's tr_ail1_list: generic_writepages write_cache_pages passing __writepage() calls clear_page_dirty_for_io which calls set_page_dirty: which calls jdata_set_page_dirty which sets PageChecked. __writepage() calls mapping->a_ops->writepage AKA gfs2_jdata_writepage However, gfs2_jdata_writepage checks if PageChecked is set, and if so, it ignores the write and redirties the page. The problem is that write_cache_pages calls clear_page_dirty_for_io, which often calls set_page_dirty(). See comments in page-writeback.c starting with "Yes, Virginia". If it's jdata, set_page_dirty will call jdata_set_page_dirty which will set PageChecked. That causes a conflict because it makes it look like the page has been redirtied by another writer, in which case we need to skip writing it and redirty the page. That ends up in a deadlock because it isn't a "real" writer and nothing will ever clear PageChecked. If we do have a real writer, it will have started a transaction. So this patch checks if a transaction is in use, and if not, it skips setting PageChecked. That way, the page will be dirtied, cleaned, and written appropriately. Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher

gfs2: don't lock sd_ail_lock in gfs2_releasepage

2020-10-15T12:29:03Z

Patch 380f7c65a7eb3288e4b6812acf3474a1de230707 changed gfs2_releasepage so that it held the sd_ail_lock spin_lock for most of its processing. It did this for some mysterious undocumented bug somewhere in the evict code path. But in the nine years since, evict has been reworked and fixed many times, and so have the transactions and ail list. I can't see a reason to hold the sd_ail_lock unless it's protecting the actual ail lists hung off the transactions. Therefore, this patch removes the locking to increase speed and efficiency, and to further help us rework the log flush code to be more concurrent with transactions. Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher

gfs2: Wipe jdata and ail1 in gfs2_journal_wipe, formerly gfs2_meta_wipe

2020-10-15T12:29:03Z

Before this patch, when blocks were freed, it called gfs2_meta_wipe to take the metadata out of the pending journal blocks. It did this mostly by calling another function called gfs2_remove_from_journal. This is shortsighted because it does not do anything with jdata blocks which may also be in the journal. This patch expands the function so that it wipes out jdata blocks from the journal as well, and it wipes it from the ail1 list if it hasn't been written back yet. Since it now processes jdata blocks as well, the function has been renamed from gfs2_meta_wipe to gfs2_journal_wipe. New function gfs2_ail1_wipe wants a static view of the ail list, so it locks the sd_ail_lock when removing items. To accomplish this, function gfs2_remove_from_journal no longer locks the sd_ail_lock, and it's now the caller's responsibility to do so. I was going to make sd_ail_lock locking conditional, but the practice is generally frowned upon. For details, see: https://lwn.net/Articles/109066/ Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher

gfs2: rename gfs2_write_full_page to gfs2_write_jdata_page, remove parm

2020-10-15T12:29:03Z

Since the function is only used for writing jdata pages, this patch simply renames function gfs2_write_full_page to a more appropriate name: gfs2_write_jdata_page. This makes the code easier to understand. The function was only called in one place, which passed in a pointer to function gfs2_get_block_noalloc. The function doesn't need to be passed in. Therefore, this also eliminates the unnecessary parameter to increase efficiency. I also took the liberty of cleaning up the function comments. Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher

gfs2: use iomap for buffered I/O in ordered and writeback mode

2020-10-14T21:54:42Z

Switch to using the iomap readpage and writepage helpers for all I/O in the ordered and writeback modes, and thus eliminate using buffer_heads for I/O in these cases. The journaled data mode is left untouched. (Andreas Gruenbacher: In gfs2_unstuffer_page, switch from mark_buffer_dirty to set_page_dirty instead of accidentally leaving the page / buffer clean.) Signed-off-by: Christoph Hellwig Signed-off-by: Andreas Gruenbacher

Merge tag 'uninit-macro-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2020-08-04T20:49:43Z

Pull uninitialized_var() macro removal from Kees Cook: "This is long overdue, and has hidden too many bugs over the years. The series has several "by hand" fixes, and then a trivial treewide replacement. - Clean up non-trivial uses of uninitialized_var() - Update documentation and checkpatch for uninitialized_var() removal - Treewide removal of uninitialized_var()" * tag 'uninit-macro-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: compiler: Remove uninitialized_var() macro treewide: Remove uninitialized_var() usage checkpatch: Remove awareness of uninitialized_var() macro mm/debug_vm_pgtable: Remove uninitialized_var() usage f2fs: Eliminate usage of uninitialized_var() macro media: sur40: Remove uninitialized_var() usage KVM: PPC: Book3S PR: Remove uninitialized_var() usage clk: spear: Remove uninitialized_var() usage clk: st: Remove uninitialized_var() usage spi: davinci: Remove uninitialized_var() usage ide: Remove uninitialized_var() usage rtlwifi: rtl8192cu: Remove uninitialized_var() usage b43: Remove uninitialized_var() usage drbd: Remove uninitialized_var() usage x86/mm/numa: Remove uninitialized_var() usage docs: deprecated.rst: Add uninitialized_var()

treewide: Remove uninitialized_var() usage

2020-07-16T19:35:15Z

Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var$([^$]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe # IB Acked-by: Kalle Valo # wireless drivers Reviewed-by: Chao Yu # erofs Signed-off-by: Kees Cook

gfs2: Rework read and page fault locking

2020-07-07T21:40:12Z

So far, gfs2 has taken the inode glocks inside the ->readpage and ->readahead address space operations. Since commit d4388340ae0b ("fs: convert mpage_readpages to mpage_readahead"), gfs2_readahead is passed the pages to read ahead locked. With that, the current holder of the inode glock may be trying to lock one of those pages while gfs2_readahead is trying to take the inode glock, resulting in a deadlock. Fix that by moving the lock taking to the higher-level ->read_iter file and ->fault vm operations. This also gets rid of an ugly lock inversion workaround in gfs2_readpage. The cache consistency model of filesystems like gfs2 is such that if data is found in the page cache, the data is up to date and can be used without taking any filesystem locks. If a page is not cached, filesystem locks must be taken before populating the page cache. To avoid taking the inode glock when the data is already cached, gfs2_file_read_iter first tries to read the data with the IOCB_NOIO flag set. If that fails, the inode glock is taken and the operation is retried with the IOCB_NOIO flag cleared. Signed-off-by: Andreas Gruenbacher

fs: convert mpage_readpages to mpage_readahead

2020-06-02T17:59:07Z

Implement the new readahead aop and convert all callers (block_dev, exfat, ext2, fat, gfs2, hpfs, isofs, jfs, nilfs2, ocfs2, omfs, qnx6, reiserfs & udf). The callers are all trivial except for GFS2 & OCFS2. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Reviewed-by: Junxiao Bi # ocfs2 Reviewed-by: Joseph Qi # ocfs2 Reviewed-by: Dave Chinner Reviewed-by: John Hubbard Reviewed-by: Christoph Hellwig Reviewed-by: William Kucharski Cc: Chao Yu Cc: Cong Wang Cc: Darrick J. Wong Cc: Eric Biggers Cc: Gao Xiang Cc: Jaegeuk Kim Cc: Michal Hocko Cc: Zi Yan Cc: Johannes Thumshirn Cc: Miklos Szeredi Link: http://lkml.kernel.org/r/20200414150233.24495-17-willy@infradead.org Signed-off-by: Linus Torvalds