jbd2: Fix possible overflow in jbd2_log_space_left()
commit add3efdd78
upstream.
When number of free space in the journal is very low, the arithmetic in
jbd2_log_space_left() could underflow resulting in very high number of
free blocks and thus triggering assertion failure in transaction commit
code complaining there's not enough space in the journal:
J_ASSERT(journal->j_free > 1);
Properly check for the low number of free blocks.
CC: stable@vger.kernel.org
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20191105164437.32602-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
parent
01e7ab5b9b
commit
1a6a96e0ff
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@ -1582,7 +1582,7 @@ static inline int jbd2_space_needed(journal_t *journal)
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static inline unsigned long jbd2_log_space_left(journal_t *journal)
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{
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/* Allow for rounding errors */
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unsigned long free = journal->j_free - 32;
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long free = journal->j_free - 32;
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if (journal->j_committing_transaction) {
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unsigned long committing = atomic_read(&journal->
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@ -1591,7 +1591,7 @@ static inline unsigned long jbd2_log_space_left(journal_t *journal)
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/* Transaction + control blocks */
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free -= committing + (committing >> JBD2_CONTROL_BLOCKS_SHIFT);
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}
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return free;
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return max_t(long, free, 0);
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}
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/*
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