Commit 721292b0 authored by Artem Bityutskiy's avatar Artem Bityutskiy Committed by Ben Hutchings

UBIFS: fix free log space calculation

commit ba29e721 upstream.

Hu (hujianyang <hujianyang@huawei.com>) discovered an issue in the
'empty_log_bytes()' function, which calculates how many bytes are left in the
log:

"
If 'c->lhead_lnum + 1 == c->ltail_lnum' and 'c->lhead_offs == c->leb_size', 'h'
would equalent to 't' and 'empty_log_bytes()' would return 'c->log_bytes'
instead of 0.
"

At this point it is not clear what would be the consequences of this, and
whether this may lead to any problems, but this patch addresses the issue just
in case.
Tested-by: default avatarhujianyang <hujianyang@huawei.com>
Reported-by: default avatarhujianyang <hujianyang@huawei.com>
Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 9cb35c87
......@@ -110,10 +110,14 @@ static inline long long empty_log_bytes(const struct ubifs_info *c)
h = (long long)c->lhead_lnum * c->leb_size + c->lhead_offs;
t = (long long)c->ltail_lnum * c->leb_size;
if (h >= t)
if (h > t)
return c->log_bytes - h + t;
else
else if (h != t)
return t - h;
else if (c->lhead_lnum != c->ltail_lnum)
return 0;
else
return c->log_bytes;
}
/**
......
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