bcachefs: Ensure buffered writes write as much as they can

This adds a new helper, bch2_folio_reservation_get_partial(), which
reserves as many blocks as possible and may return partial success.

__bch2_buffered_write() is switched to the new helper - this fixes
fstests generic/275, the write until -ENOSPC test.

generic/230 now fails: this appears to be a test bug, where xfs_io isn't
looping after a partial write to get the error code.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/fs-io-buffered.c b/fs/bcachefs/fs-io-buffered.c
index 1355d618f9883c6b9f410e61b3e949ea58626f34..cc33d763f7221d21c39bed6b66f4ccb9f95e5cd5 100644 (file)
--- a/fs/bcachefs/fs-io-buffered.c
+++ b/fs/bcachefs/fs-io-buffered.c
@@ -863,24 +863,26 @@ static int __bch2_buffered_write(struct bch_inode_info *inode,
        f_pos = pos;
        f_offset = pos - folio_pos(darray_first(fs));
        darray_for_each(fs, fi) {
+               ssize_t f_reserved;
+
                f = *fi;
                f_len = min(end, folio_end_pos(f)) - f_pos;
+               f_reserved = bch2_folio_reservation_get_partial(c, inode, f, &res, f_offset, f_len);
+
+               if (unlikely(f_reserved != f_len)) {
+                       if (f_reserved < 0) {
+                               if (f == darray_first(fs)) {
+                                       ret = f_reserved;
+                                       goto out;
+                               }
+
+                               folios_trunc(&fs, fi);
+                               end = min(end, folio_end_pos(darray_last(fs)));
+                       } else {
+                               folios_trunc(&fs, fi + 1);
+                               end = f_pos + f_reserved;
+                       }
 
-               /*
-                * XXX: per POSIX and fstests generic/275, on -ENOSPC we're
-                * supposed to write as much as we have disk space for.
-                *
-                * On failure here we should still write out a partial page if
-                * we aren't completely out of disk space - we don't do that
-                * yet:
-                */
-               ret = bch2_folio_reservation_get(c, inode, f, &res, f_offset, f_len);
-               if (unlikely(ret)) {
-                       folios_trunc(&fs, fi);
-                       if (!fs.nr)
-                               goto out;
-
-                       end = min(end, folio_end_pos(darray_last(fs)));
                        break;
                }
 

diff --git a/fs/bcachefs/fs-io-pagecache.c b/fs/bcachefs/fs-io-pagecache.c
index 872283e5bd1e2265ddbcc315b2b0cdfe7606dbc8..a9cc5cad9cc992ff6d1e3d9000c0a51b9b85408f 100644 (file)
--- a/fs/bcachefs/fs-io-pagecache.c
+++ b/fs/bcachefs/fs-io-pagecache.c
@@ -423,7 +423,7 @@ int bch2_folio_reservation_get(struct bch_fs *c,
                        struct bch_inode_info *inode,
                        struct folio *folio,
                        struct bch2_folio_reservation *res,
-                       unsigned offset, unsigned len)
+                       size_t offset, size_t len)
 {
        struct bch_folio *s = bch2_folio_create(folio, 0);
        unsigned i, disk_sectors = 0, quota_sectors = 0;
@@ -437,8 +437,7 @@ int bch2_folio_reservation_get(struct bch_fs *c,
        for (i = round_down(offset, block_bytes(c)) >> 9;
             i < round_up(offset + len, block_bytes(c)) >> 9;
             i++) {
-               disk_sectors += sectors_to_reserve(&s->s[i],
-                                               res->disk.nr_replicas);
+               disk_sectors += sectors_to_reserve(&s->s[i], res->disk.nr_replicas);
                quota_sectors += s->s[i].state == SECTOR_unallocated;
        }
 
@@ -449,12 +448,9 @@ int bch2_folio_reservation_get(struct bch_fs *c,
        }
 
        if (quota_sectors) {
-               ret = bch2_quota_reservation_add(c, inode, &res->quota,
-                                                quota_sectors, true);
+               ret = bch2_quota_reservation_add(c, inode, &res->quota, quota_sectors, true);
                if (unlikely(ret)) {
-                       struct disk_reservation tmp = {
-                               .sectors = disk_sectors
-                       };
+                       struct disk_reservation tmp = { .sectors = disk_sectors };
 
                        bch2_disk_reservation_put(c, &tmp);
                        res->disk.sectors -= disk_sectors;
@@ -465,6 +461,31 @@ int bch2_folio_reservation_get(struct bch_fs *c,
        return 0;
 }
 
+ssize_t bch2_folio_reservation_get_partial(struct bch_fs *c,
+                       struct bch_inode_info *inode,
+                       struct folio *folio,
+                       struct bch2_folio_reservation *res,
+                       size_t offset, size_t len)
+{
+       size_t l, reserved = 0;
+       int ret;
+
+       while ((l = len - reserved)) {
+               while ((ret = bch2_folio_reservation_get(c, inode, folio, res, offset, l))) {
+                       if ((offset & (block_bytes(c) - 1)) + l <= block_bytes(c))
+                               return reserved ?: ret;
+
+                       len = reserved + l;
+                       l /= 2;
+               }
+
+               offset += l;
+               reserved += l;
+       }
+
+       return reserved;
+}
+
 static void bch2_clear_folio_bits(struct folio *folio)
 {
        struct bch_inode_info *inode = to_bch_ei(folio->mapping->host);

diff --git a/fs/bcachefs/fs-io-pagecache.h b/fs/bcachefs/fs-io-pagecache.h
index 828c3d7c8f1993129ae54db922f4bf9a649f6b6b..fd7d692c087e1d7e8425007a90bf115bed2e5dc6 100644 (file)
--- a/fs/bcachefs/fs-io-pagecache.h
+++ b/fs/bcachefs/fs-io-pagecache.h
@@ -153,7 +153,12 @@ int bch2_folio_reservation_get(struct bch_fs *,
                        struct bch_inode_info *,
                        struct folio *,
                        struct bch2_folio_reservation *,
-                       unsigned, unsigned);
+                       size_t, size_t);
+ssize_t bch2_folio_reservation_get_partial(struct bch_fs *,
+                       struct bch_inode_info *,
+                       struct folio *,
+                       struct bch2_folio_reservation *,
+                       size_t, size_t);
 
 void bch2_set_folio_dirty(struct bch_fs *,
                          struct bch_inode_info *,