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UBIFS: fix free log space calculation 

commit ba29e721eb 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: hujianyang <hujianyang@huawei.com>
Reported-by: hujianyang <hujianyang@huawei.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Artem Bityutskiy 2014-07-16 15:22:29 +03:00 committed by Greg Kroah-Hartman
parent c68ab2f9d4
commit d53133bd0c
1 changed files with 6 additions and 2 deletions
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8
fs/ubifs/log.c
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@ -106,10 +106,14 @@ 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;
}
/**