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Date: Mon, 3 Feb 2014 13:38:18 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
Cc: LKML <linux-kernel@...r.kernel.org>,
linux-nilfs <linux-nilfs@...r.kernel.org>,
Andreas Rohner <andreas.rohner@....net>
Subject: Re: [PATCH 3/4] nilfs2: add nilfs_sufile_set_suinfo to update
segment usage
On Tue, 4 Feb 2014 01:50:43 +0900 Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp> wrote:
> From: Andreas Rohner <andreas.rohner@....net>
>
> This patch introduces the nilfs_sufile_set_suinfo function, which
> expects an array of nilfs_suinfo_update structures and updates the
> segment usage information accordingly.
>
> This is basically a helper function for the newly introduced
> NILFS_IOCTL_SET_SUINFO ioctl.
>
> ..
>
> --- a/fs/nilfs2/sufile.c
> +++ b/fs/nilfs2/sufile.c
> @@ -870,6 +870,137 @@ ssize_t nilfs_sufile_get_suinfo(struct inode *sufile, __u64 segnum, void *buf,
> }
>
> /**
> + * nilfs_sufile_set_suinfo - sets segment usage info
> + * @sufile: inode of segment usage file
> + * @buf: array of suinfo_update
> + * @supsz: byte size of suinfo_update
> + * @nsup: size of suinfo_update array
> + *
> + * Description: Takes an array of nilfs_suinfo_update structs and updates
> + * segment usage accordingly. Only the fields indicated by the sup_flags
> + * are updated.
> + *
> + * Return Value: On success, 0 is returned. On error, one of the
> + * following negative error codes is returned.
> + *
> + * %-EIO - I/O error.
> + *
> + * %-ENOMEM - Insufficient amount of memory available.
> + *
> + * %-EINVAL - Invalid values in input (segment number, flags or nblocks)
> + */
> +ssize_t nilfs_sufile_set_suinfo(struct inode *sufile, void *buf,
> + unsigned supsz, size_t nsup)
> +{
> + struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
> + struct buffer_head *header_bh, *bh;
> + struct nilfs_suinfo_update *sup, *supend = buf + supsz * nsup;
> + struct nilfs_segment_usage *su;
> + void *kaddr;
> + unsigned long blkoff, prev_blkoff;
> + int cleansi, cleansu, dirtysi, dirtysu;
> + long ncleaned = 0, ndirtied = 0;
> + int ret = 0;
> +
> + if (unlikely(nsup == 0))
> + return ret;
> +
> + for (sup = buf; sup < supend; sup = (void *)sup + supsz) {
> + if (sup->sup_segnum >= nilfs->ns_nsegments
> + || (sup->sup_flags &
> + (~0UL << __NR_NILFS_SUINFO_UPDATE_FIELDS))
> + || (nilfs_suinfo_update_nblocks(sup) &&
> + sup->sup_sui.sui_nblocks >
> + nilfs->ns_blocks_per_segment))
> + return -EINVAL;
> + }
> +
> + down_write(&NILFS_MDT(sufile)->mi_sem);
> +
> + ret = nilfs_sufile_get_header_block(sufile, &header_bh);
> + if (ret < 0)
> + goto out_sem;
> +
> + sup = buf;
> + blkoff = nilfs_sufile_get_blkoff(sufile, sup->sup_segnum);
> + ret = nilfs_mdt_get_block(sufile, blkoff, 1, NULL, &bh);
> + if (ret < 0)
> + goto out_header;
> +
> + for (;;) {
> + kaddr = kmap_atomic(bh->b_page);
Can this buffer_head really be in highmem?
> + su = nilfs_sufile_block_get_segment_usage(
> + sufile, sup->sup_segnum, bh, kaddr);
Returns an address wthin the kmapped page. I really hope
nilfs_sufile_block_get_segment_usage() cannot return an address outside
that page - it appears to do quite a lot of unchecked arithmetic which
is dependent on stuff which was read from the disk. What it that was
interfered with or otherwise corrupted?
> + if (nilfs_suinfo_update_lastmod(sup))
> + su->su_lastmod = cpu_to_le64(sup->sup_sui.sui_lastmod);
> +
> + if (nilfs_suinfo_update_nblocks(sup))
> + su->su_nblocks = cpu_to_le32(sup->sup_sui.sui_nblocks);
> +
> + if (nilfs_suinfo_update_flags(sup)) {
> + /*
> + * Active flag is a virtual flag projected by running
> + * nilfs kernel code - drop it not to write it to
> + * disk.
> + */
> + sup->sup_sui.sui_flags &=
> + ~(1UL << NILFS_SEGMENT_USAGE_ACTIVE);
> +
> + cleansi = nilfs_suinfo_clean(&sup->sup_sui);
> + cleansu = nilfs_segment_usage_clean(su);
> + dirtysi = nilfs_suinfo_dirty(&sup->sup_sui);
> + dirtysu = nilfs_segment_usage_dirty(su);
> +
> + if (cleansi && !cleansu)
> + ++ncleaned;
> + else if (!cleansi && cleansu)
> + --ncleaned;
> +
> + if (dirtysi && !dirtysu)
> + ++ndirtied;
> + else if (!dirtysi && dirtysu)
> + --ndirtied;
> +
> + su->su_flags = cpu_to_le32(sup->sup_sui.sui_flags);
> + }
> +
> + kunmap_atomic(kaddr);
flush_dcache_page()? Can the page be mapped by userspace?
> + sup = (void *)sup + supsz;
> + if (sup >= supend)
> + break;
> +
> + prev_blkoff = blkoff;
> + blkoff = nilfs_sufile_get_blkoff(sufile, sup->sup_segnum);
> + if (blkoff == prev_blkoff)
> + continue;
> +
> + /* get different block */
> + mark_buffer_dirty(bh);
> + brelse(bh);
put_bh() will suffice - we know bh != NULL.
> + ret = nilfs_mdt_get_block(sufile, blkoff, 1, NULL, &bh);
> + if (unlikely(ret < 0))
> + goto out_mark;
> + }
> + mark_buffer_dirty(bh);
> + brelse(bh);
ditto
> + out_mark:
> + if (ncleaned || ndirtied) {
> + nilfs_sufile_mod_counter(header_bh, (u64)ncleaned,
> + (u64)ndirtied);
> + NILFS_SUI(sufile)->ncleansegs += ncleaned;
> + }
> + nilfs_mdt_mark_dirty(sufile);
> + out_header:
> + brelse(header_bh);
> + out_sem:
> + up_write(&NILFS_MDT(sufile)->mi_sem);
> + return ret;
> +}
> +
> +/**
--
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