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| author | Artem Bityutskiy <Artem.Bityutskiy@nokia.com> | 2008-09-03 16:17:14 +0300 |
|---|---|---|
| committer | Artem Bityutskiy <Artem.Bityutskiy@nokia.com> | 2008-09-05 20:01:59 +0300 |
| commit | f171d4d769c8ccac6675892960e37f6485837fae (patch) | |
| tree | 60236e7749d9e9e8bd7a383214fba6aaaa6dcb2d /fs | |
| parent | 7c7cbadf7341a0792879c67d6e3020f040d6cd7f (diff) | |
| download | lwn-f171d4d769c8ccac6675892960e37f6485837fae.tar.gz lwn-f171d4d769c8ccac6675892960e37f6485837fae.zip | |
UBIFS: fix division by zero
If fanout is 3, we have division by zero in
'ubifs_read_superblock()':
divide error: 0000 [#1] PREEMPT SMP
Pid: 28744, comm: mount Not tainted (2.6.27-rc4-ubifs-2.6 #23)
EIP: 0060:[<f8f9e3ef>] EFLAGS: 00010202 CPU: 0
EIP is at ubifs_reported_space+0x2d/0x69 [ubifs]
EAX: 00000000 EBX: 00000000 ECX: 00000000 EDX: 00000000
ESI: 00000000 EDI: f0ae64b0 EBP: f1f9fcf4 ESP: f1f9fce0
DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ubifs/budget.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c index 101d278c591d..73db464cd08b 100644 --- a/fs/ubifs/budget.c +++ b/fs/ubifs/budget.c @@ -723,24 +723,25 @@ void ubifs_release_dirty_inode_budget(struct ubifs_info *c, */ long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free) { - int divisor, factor; + int divisor, factor, f; /* * Reported space size is @free * X, where X is UBIFS block size * divided by UBIFS block size + all overhead one data block * introduces. The overhead is the node header + indexing overhead. * - * Indexing overhead is calculations are based on the following - * formula: I = N/(f - 1) + 1, where I - number of indexing nodes, N - - * number of data nodes, f - fanout. Because effective UBIFS fanout is - * twice as less than maximum fanout, we assume that each data node + * Indexing overhead calculations are based on the following formula: + * I = N/(f - 1) + 1, where I - number of indexing nodes, N - number + * of data nodes, f - fanout. Because effective UBIFS fanout is twice + * as less than maximum fanout, we assume that each data node * introduces 3 * @c->max_idx_node_sz / (@c->fanout/2 - 1) bytes. * Note, the multiplier 3 is because UBIFS reseves thrice as more space * for the index. */ + f = c->fanout > 3 ? c->fanout >> 1 : 2; factor = UBIFS_BLOCK_SIZE; divisor = UBIFS_MAX_DATA_NODE_SZ; - divisor += (c->max_idx_node_sz * 3) / ((c->fanout >> 1) - 1); + divisor += (c->max_idx_node_sz * 3) / (f - 1); free *= factor; do_div(free, divisor); return free; |