| From | David Howells <> | Subject | Re: [PATCH 18/19] ext4: Add example fsinfo information [ver #16] | Date | Fri, 21 Feb 2020 14:43:05 +0000 |
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Darrick J. Wong <darrick.wong@oracle.com> wrote:
> > + memcpy(ctx->buffer, es->s_volume_name, sizeof(es->s_volume_name)); > > Shouldn't this be checking that ctx->buffer is large enough to hold > s_volume_name?
Well, the buffer is guaranteed to be 4KiB in size.
> > + return strlen(ctx->buffer); > > s_volume_name is /not/ a null-terminated string if the label is 16 > characters long.
And the buffer is precleared, so it's automatically NULL terminated.
> > +#define FSINFO_ATTR_EXT4_TIMESTAMPS 0x400 /* Ext4 superblock timestamps */ > > I guess each filesystem gets ... 256 different attrs, and the third > nibble determines the namespace?
No. Think of it as allocating namespace in 256-number blocks. That means there are 16 million of them. If a filesystem uses up an entire block, it can always allocate another one. I don't think it likely that we'll get sufficient filesystems to eat them all.
David
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