7f93cff90f
Commit 84061e0 fixed an accounting bug only to introduce the
possibility of a kernel OOPS if the journal has a non-zero j_errno
field indicating that the file system had detected a fs inconsistency.
After the journal replay, if the journal superblock indicates that the
file system has an error, this indication is transfered to the file
system and then ext4_commit_super() is called to write this to the
disk.
But since the percpu counters are now initialized after the journal
replay, the call to ext4_commit_super() will cause a kernel oops since
it needs to use the percpu counters the ext4 superblock structure.
The fix is to skip setting the ext4 free block and free inode fields
if the percpu counter has not been set.
Thanks to Ken Sumrall for reporting and analyzing the root causes of
this bug.
Addresses-Google-Bug: #3054080
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
174 lines
3.7 KiB
C
174 lines
3.7 KiB
C
#ifndef _LINUX_PERCPU_COUNTER_H
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#define _LINUX_PERCPU_COUNTER_H
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/*
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* A simple "approximate counter" for use in ext2 and ext3 superblocks.
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*
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* WARNING: these things are HUGE. 4 kbytes per counter on 32-way P4.
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*/
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#include <linux/spinlock.h>
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#include <linux/smp.h>
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#include <linux/list.h>
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#include <linux/threads.h>
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#include <linux/percpu.h>
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#include <linux/types.h>
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#ifdef CONFIG_SMP
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struct percpu_counter {
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spinlock_t lock;
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s64 count;
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#ifdef CONFIG_HOTPLUG_CPU
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struct list_head list; /* All percpu_counters are on a list */
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#endif
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s32 __percpu *counters;
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};
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extern int percpu_counter_batch;
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int __percpu_counter_init(struct percpu_counter *fbc, s64 amount,
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struct lock_class_key *key);
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#define percpu_counter_init(fbc, value) \
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({ \
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static struct lock_class_key __key; \
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\
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__percpu_counter_init(fbc, value, &__key); \
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})
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void percpu_counter_destroy(struct percpu_counter *fbc);
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void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
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void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
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s64 __percpu_counter_sum(struct percpu_counter *fbc);
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int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs);
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static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
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{
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__percpu_counter_add(fbc, amount, percpu_counter_batch);
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}
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static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
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{
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s64 ret = __percpu_counter_sum(fbc);
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return ret < 0 ? 0 : ret;
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}
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static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
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{
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return __percpu_counter_sum(fbc);
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}
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static inline s64 percpu_counter_read(struct percpu_counter *fbc)
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{
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return fbc->count;
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}
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/*
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* It is possible for the percpu_counter_read() to return a small negative
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* number for some counter which should never be negative.
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*
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*/
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static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
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{
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s64 ret = fbc->count;
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barrier(); /* Prevent reloads of fbc->count */
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if (ret >= 0)
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return ret;
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return 1;
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}
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static inline int percpu_counter_initialized(struct percpu_counter *fbc)
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{
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return (fbc->counters != NULL);
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}
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#else
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struct percpu_counter {
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s64 count;
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};
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static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
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{
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fbc->count = amount;
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return 0;
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}
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static inline void percpu_counter_destroy(struct percpu_counter *fbc)
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{
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}
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static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
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{
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fbc->count = amount;
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}
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static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
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{
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if (fbc->count > rhs)
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return 1;
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else if (fbc->count < rhs)
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return -1;
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else
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return 0;
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}
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static inline void
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percpu_counter_add(struct percpu_counter *fbc, s64 amount)
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{
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preempt_disable();
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fbc->count += amount;
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preempt_enable();
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}
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static inline void
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__percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
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{
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percpu_counter_add(fbc, amount);
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}
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static inline s64 percpu_counter_read(struct percpu_counter *fbc)
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{
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return fbc->count;
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}
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static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
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{
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return fbc->count;
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}
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static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
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{
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return percpu_counter_read_positive(fbc);
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}
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static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
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{
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return percpu_counter_read(fbc);
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}
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static inline int percpu_counter_initialized(struct percpu_counter *fbc)
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{
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return 1;
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}
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#endif /* CONFIG_SMP */
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static inline void percpu_counter_inc(struct percpu_counter *fbc)
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{
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percpu_counter_add(fbc, 1);
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}
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static inline void percpu_counter_dec(struct percpu_counter *fbc)
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{
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percpu_counter_add(fbc, -1);
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}
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static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
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{
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percpu_counter_add(fbc, -amount);
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}
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#endif /* _LINUX_PERCPU_COUNTER_H */
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