From 70d41c9e276c5e7b130d328a6ece92c9130a6572 Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Sun, 28 May 2023 00:35:35 -0400
Subject: [PATCH] bcachefs: Avoid __GFP_NOFAIL
We've been using __GFP_NOFAIL for allocating struct bch_folio, our
private per-folio state.
However, that struct is variable size - it holds state for each sector
in the folio, and folios can be quite large now, which means it's
possible for bch_folio to be larger than PAGE_SIZE now.
__GFP_NOFAIL allocations are undesirable in normal circumstances, but
particularly so at >= PAGE_SIZE, and warnings are emitted for that.
So, this patch adds proper error paths and eliminates most uses of
__GFP_NOFAIL. Also, do some more cleanup of gfp flags w.r.t. btree node
locks: we can use GFP_KERNEL, but only if we're not holding btree locks,
and if we are holding btree locks we should be using GFP_NOWAIT.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
fs/bcachefs/fs-io.c | 91 +++++++++++++++++++++++++--------------------
1 file changed, 50 insertions(+), 41 deletions(-)
diff --git a/fs/bcachefs/fs-io.c b/fs/bcachefs/fs-io.c
index 64897cee84943..cf48f9a0d4e1f 100644
--- a/fs/bcachefs/fs-io.c
+++ b/fs/bcachefs/fs-io.c
@@ -574,7 +574,7 @@ static struct bch_folio *__bch2_folio_create(struct folio *folio, gfp_t gfp)
s = kzalloc(sizeof(*s) +
sizeof(struct bch_folio_sector) *
- folio_sectors(folio), GFP_NOFS|gfp);
+ folio_sectors(folio), gfp);
if (!s)
return NULL;
@@ -601,7 +601,7 @@ static void __bch2_folio_set(struct folio *folio,
unsigned pg_offset, unsigned pg_len,
unsigned nr_ptrs, unsigned state)
{
- struct bch_folio *s = bch2_folio_create(folio, __GFP_NOFAIL);
+ struct bch_folio *s = bch2_folio(folio);
unsigned i, sectors = folio_sectors(folio);
BUG_ON(pg_offset >= sectors);
@@ -630,11 +630,25 @@ static int bch2_folio_set(struct bch_fs *c, subvol_inum inum,
struct btree_trans trans;
struct btree_iter iter;
struct bkey_s_c k;
+ struct bch_folio *s;
u64 offset = folio_sector(folios[0]);
- unsigned folio_idx = 0;
+ unsigned folio_idx;
u32 snapshot;
+ bool need_set = false;
int ret;
+ for (folio_idx = 0; folio_idx < nr_folios; folio_idx++) {
+ s = bch2_folio_create(folios[folio_idx], GFP_KERNEL);
+ if (!s)
+ return -ENOMEM;
+
+ need_set |= !s->uptodate;
+ }
+
+ if (!need_set)
+ return 0;
+
+ folio_idx = 0;
bch2_trans_init(&trans, c, 0, 0);
retry:
bch2_trans_begin(&trans);
@@ -659,7 +673,7 @@ retry:
BUG_ON(k.k->p.offset < folio_start);
BUG_ON(bkey_start_offset(k.k) > folio_end);
- if (!bch2_folio_create(folio, __GFP_NOFAIL)->uptodate)
+ if (!bch2_folio(folio)->uptodate)
__bch2_folio_set(folio, folio_offset, folio_len, nr_ptrs, state);
if (k.k->p.offset < folio_end)
@@ -1051,15 +1065,8 @@ vm_fault_t bch2_page_mkwrite(struct vm_fault *vmf)
len = min_t(loff_t, folio_size(folio), isize - folio_pos(folio));
- if (!bch2_folio_create(folio, __GFP_NOFAIL)->uptodate) {
- if (bch2_folio_set(c, inode_inum(inode), &folio, 1)) {
- folio_unlock(folio);
- ret = VM_FAULT_SIGBUS;
- goto out;
- }
- }
-
- if (bch2_folio_reservation_get(c, inode, folio, &res, 0, len)) {
+ if (bch2_folio_set(c, inode_inum(inode), &folio, 1) ?:
+ bch2_folio_reservation_get(c, inode, folio, &res, 0, len)) {
folio_unlock(folio);
ret = VM_FAULT_SIGBUS;
goto out;
@@ -1139,7 +1146,7 @@ static int readpages_iter_init(struct readpages_iter *iter,
darray_for_each(iter->folios, fi) {
ractl->_nr_pages -= 1U << folio_order(*fi);
- __bch2_folio_create(*fi, __GFP_NOFAIL);
+ __bch2_folio_create(*fi, __GFP_NOFAIL|GFP_KERNEL);
folio_put(*fi);
folio_put(*fi);
}
@@ -1171,11 +1178,15 @@ static bool extent_partial_reads_expensive(struct bkey_s_c k)
return false;
}
-static void readpage_bio_extend(struct readpages_iter *iter,
- struct bio *bio,
- unsigned sectors_this_extent,
- bool get_more)
+static int readpage_bio_extend(struct btree_trans *trans,
+ struct readpages_iter *iter,
+ struct bio *bio,
+ unsigned sectors_this_extent,
+ bool get_more)
{
+ /* Don't hold btree locks while allocating memory: */
+ bch2_trans_unlock(trans);
+
while (bio_sectors(bio) < sectors_this_extent &&
bio->bi_vcnt < bio->bi_max_vecs) {
struct folio *folio = readpage_iter_peek(iter);
@@ -1197,12 +1208,12 @@ static void readpage_bio_extend(struct readpages_iter *iter,
if (!folio)
break;
- if (!__bch2_folio_create(folio, 0)) {
+ if (!__bch2_folio_create(folio, GFP_KERNEL)) {
folio_put(folio);
break;
}
- ret = filemap_add_folio(iter->mapping, folio, folio_offset, GFP_NOFS);
+ ret = filemap_add_folio(iter->mapping, folio, folio_offset, GFP_KERNEL);
if (ret) {
__bch2_folio_release(folio);
folio_put(folio);
@@ -1216,6 +1227,8 @@ static void readpage_bio_extend(struct readpages_iter *iter,
BUG_ON(!bio_add_folio(bio, folio, folio_size(folio), 0));
}
+
+ return bch2_trans_relock(trans);
}
static void bchfs_read(struct btree_trans *trans,
@@ -1283,9 +1296,12 @@ retry:
sectors = min(sectors, k.k->size - offset_into_extent);
- if (readpages_iter)
- readpage_bio_extend(readpages_iter, &rbio->bio, sectors,
- extent_partial_reads_expensive(k));
+ if (readpages_iter) {
+ ret = readpage_bio_extend(trans, readpages_iter, &rbio->bio, sectors,
+ extent_partial_reads_expensive(k));
+ if (ret)
+ break;
+ }
bytes = min(sectors, bio_sectors(&rbio->bio)) << 9;
swap(rbio->bio.bi_iter.bi_size, bytes);
@@ -1594,7 +1610,7 @@ static int __bch2_writepage(struct folio *folio,
folio_size(folio));
do_io:
f_sectors = folio_sectors(folio);
- s = bch2_folio_create(folio, __GFP_NOFAIL);
+ s = bch2_folio(folio);
if (f_sectors > w->tmp_sectors) {
kfree(w->tmp);
@@ -1776,11 +1792,9 @@ readpage:
if (ret)
goto err;
out:
- if (!bch2_folio_create(folio, __GFP_NOFAIL)->uptodate) {
- ret = bch2_folio_set(c, inode_inum(inode), &folio, 1);
- if (ret)
- goto err;
- }
+ ret = bch2_folio_set(c, inode_inum(inode), &folio, 1);
+ if (ret)
+ goto err;
ret = bch2_folio_reservation_get(c, inode, folio, res, offset, len);
if (ret) {
@@ -1916,19 +1930,16 @@ static int __bch2_buffered_write(struct bch_inode_info *inode,
}
}
+ ret = bch2_folio_set(c, inode_inum(inode), folios.data, folios.nr);
+ if (ret)
+ goto out;
+
f_pos = pos;
f_offset = pos - folio_pos(darray_first(folios));
darray_for_each(folios, fi) {
struct folio *f = *fi;
u64 f_len = min(end, folio_end_pos(f)) - f_pos;
- if (!bch2_folio_create(f, __GFP_NOFAIL)->uptodate) {
- ret = bch2_folio_set(c, inode_inum(inode), fi,
- folios.data + folios.nr - fi);
- if (ret)
- goto out;
- }
-
/*
* XXX: per POSIX and fstests generic/275, on -ENOSPC we're
* supposed to write as much as we have disk space for.
@@ -2884,11 +2895,9 @@ static int __bch2_truncate_folio(struct bch_inode_info *inode,
goto unlock;
}
- if (!s->uptodate) {
- ret = bch2_folio_set(c, inode_inum(inode), &folio, 1);
- if (ret)
- goto unlock;
- }
+ ret = bch2_folio_set(c, inode_inum(inode), &folio, 1);
+ if (ret)
+ goto unlock;
for (i = round_up(start_offset, block_bytes(c)) >> 9;
i < round_down(end_offset, block_bytes(c)) >> 9;
--
2.30.2