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Message-ID: <20150826161145.GF14012@quack.suse.cz>
Date: Wed, 26 Aug 2015 18:11:45 +0200
From: Jan Kara <jack@...e.cz>
To: Andreas Dilger <adilger@...ger.ca>
Cc: Jan Kara <jack@...e.com>, linux-ext4@...r.kernel.org,
Ted Tso <tytso@....edu>,
"Darrick J. Wong" <darrick.wong@...cle.com>
Subject: Re: [PATCH 13/19] tune2fs: Add support for changing number of
reserved inodes
On Fri 07-08-15 12:58:49, Andreas Dilger wrote:
> On Aug 7, 2015, at 4:51 AM, Jan Kara <jack@...e.com> wrote:
> >
> > Signed-off-by: Jan Kara <jack@...e.com>
> > ---
> > misc/tune2fs.8.in | 5 +++
> > misc/tune2fs.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 107 insertions(+)
> >
> > diff --git a/misc/tune2fs.8.in b/misc/tune2fs.8.in
> > index 4373fc49b255..922705329112 100644
> > --- a/misc/tune2fs.8.in
> > +++ b/misc/tune2fs.8.in
> > @@ -236,6 +236,11 @@ program.
> > This superblock setting is only honored in 2.6.35+ kernels;
> > and not at all by the ext2 and ext3 file system drivers.
> > .TP
> > +.BI reserved_inodes= number_of_reserved_inodes
> > +Set the number of inodes reserved for system files. This number must be
> > +at least 10. Currently 10 is enough but future features may require additional
> > +reserved inodes. Reserving more inodes requires full file system scan so it
> > +can take a long time.
> > .B test_fs
> > Set a flag in the filesystem superblock indicating that it may be
> > mounted using experimental kernel code, such as the ext4dev filesystem.
> > diff --git a/misc/tune2fs.c b/misc/tune2fs.c
> > index d6bfad3374d1..d6e75fe00814 100644
> > --- a/misc/tune2fs.c
> > +++ b/misc/tune2fs.c
> > @@ -92,6 +92,7 @@ static char *features_cmd;
> > static char *mntopts_cmd;
> > static int stride, stripe_width;
> > static int stride_set, stripe_width_set;
> > +static unsigned long new_first_ino;
> > static char *extended_cmd;
> > static unsigned long new_inode_size;
> > static char *ext_mount_opts;
> > @@ -2298,6 +2299,34 @@ static int parse_extended_opts(ext2_filsys fs, const char *opts)
> > continue;
> > }
> > ext_mount_opts = strdup(arg);
> > + } else if (!strcmp(token, "reserved_inodes")) {
> > + if (!arg) {
> > + r_usage++;
> > + continue;
> > + }
> > + new_first_ino = strtoul(arg, &p, 0);
> > + if (*p) {
> > + fprintf(stderr,
> > + _("Invalid number of reserved inodes "
> > + "%s\n"),
> > + arg);
> > + r_usage++;
> > + continue;
> > + }
> > + /* Ino 0 is invalid so bump by 1... */
> > + new_first_ino++;
> > + if (new_first_ino < EXT2_GOOD_OLD_FIRST_INO) {
> > + fprintf(stderr,
> > + _("Too few reserved inodes "
> > + "%s (must be at least %u)\n"),
> > + arg, EXT2_GOOD_OLD_FIRST_INO - 1);
> > + r_usage++;
> > + continue;
> > + }
> > + /*
> > + * Here should go further feature tests to disallow
> > + * admin to free used system inode
> > + */
>
> Not only should this check that the new_first_ino isn't shrinking too
> small to cover in-use special inodes, it should also verify that it
> isn't growing to cover in-use normal inodes (e.g. lost+found).
>
> I guess one option might be to reserve "12" for the lost+found inode,
> since virtually all filesystems have it this way (though not all),
> and it would also help e2fsck in the future if it didn't need to
> allocate some other inode for lost+found in case of corruption.
We do take care to move any normal inodes that are in the way. So this
isn't an issue... That's why I had to refactor all the resize code after
all...
Honza
>
> Cheers, Andreas
>
> > } else
> > r_usage++;
> > }
> > @@ -2312,6 +2341,7 @@ static int parse_extended_opts(ext2_filsys fs, const char *opts)
> > "\tmount_opts=<extended default mount options>\n"
> > "\tstride=<RAID per-disk chunk size in blocks>\n"
> > "\tstripe_width=<RAID stride*data disks in blocks>\n"
> > + "\treserved_inodes=<number of reserved inodes>\n"
> > "\ttest_fs\n"
> > "\t^test_fs\n"));
> > free(buf);
> > @@ -2986,6 +3016,75 @@ fs_update_journal_user(struct ext2_super_block *sb, __u8 old_uuid[UUID_SIZE])
> > return 0;
> > }
> >
> > +/* Zero range of inodes and mark them as free / used */
> > +static errcode_t zero_inodes_range(ext2_filsys fs, ext2_ino_t start,
> > + ext2_ino_t end, int inuse)
> > +{
> > + char *inode;
> > + int length = EXT2_INODE_SIZE(fs->super);
> > + ext2_ino_t ino;
> > + errcode_t retval;
> > +
> > + retval = ext2fs_get_memzero(length, &inode);
> > + if (retval)
> > + return retval;
> > +
> > + for (ino = start; ino <= end; ino++) {
> > + ext2fs_inode_alloc_stats(fs, ino, inuse);
> > + retval = ext2fs_write_inode_full(fs, ino,
> > + (struct ext2_inode *)inode,
> > + length);
> > + if (retval)
> > + break;
> > + }
> > + ext2fs_free_mem(inode);
> > +
> > + return retval;
> > +}
> > +
> > +static errcode_t update_reserved_inodes(ext2_filsys fs)
> > +{
> > + errcode_t retval = 0;
> > + ext2fs_inode_bitmap imap;
> > + ext2_ino_t ino, first_ino = fs->super->s_first_ino;
> > +
> > + if (new_first_ino == first_ino)
> > + return 0;
> > +
> > + /* Group descriptors will need writing as well */
> > + fs->flags &= ~EXT2_FLAG_SUPER_ONLY;
> > +
> > + /* Freeing reserved inodes is easy */
> > + if (new_first_ino < first_ino) {
> > + retval = zero_inodes_range(fs, new_first_ino, first_ino - 1,
> > + -1);
> > + if (retval)
> > + return retval;
> > + goto out;
> > + }
> > +
> > + retval = ext2fs_allocate_inode_bitmap(fs, "inodes to move", &imap);
> > + if (retval)
> > + return retval;
> > +
> > + for (ino = fs->super->s_first_ino; ino < new_first_ino; ino++)
> > + ext2fs_mark_inode_bitmap2(imap, ino);
> > +
> > + retval = ext2fs_move_inodes(fs, imap);
> > + ext2fs_free_inode_bitmap(imap);
> > + if (retval)
> > + return retval;
> > +
> > + retval = zero_inodes_range(fs, first_ino, new_first_ino - 1, +1);
> > + if (retval)
> > + return retval;
> > +out:
> > + fs->super->s_first_ino = new_first_ino;
> > + ext2fs_mark_super_dirty(fs);
> > +
> > + return 0;
> > +}
> > +
> > int main(int argc, char **argv)
> > {
> > errcode_t retval;
> > @@ -3404,6 +3503,9 @@ retry_open:
> > if (feature_64bit)
> > convert_64bit(&fs, feature_64bit);
> >
> > + if (new_first_ino)
> > + update_reserved_inodes(fs);
> > +
> > if (rewrite_checksums)
> > rewrite_metadata_checksums(fs);
> >
> > --
> > 2.1.4
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> > the body of a message to majordomo@...r.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>
> Cheers, Andreas
>
>
>
>
>
>
--
Jan Kara <jack@...e.com>
SUSE Labs, CR
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