From f9a61eb4e2471c56a63cd804c7474128138c38ac Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 22 Feb 2016 11:49:09 -0500 Subject: mbcache2: reimplement mbcache Original mbcache was designed to have more features than what ext? filesystems ended up using. It supported entry being in more hashes, it had a home-grown rwlocking of each entry, and one cache could cache entries from multiple filesystems. This genericity also resulted in more complex locking, larger cache entries, and generally more code complexity. This is reimplementation of the mbcache functionality to exactly fit the purpose ext? filesystems use it for. Cache entries are now considerably smaller (7 instead of 13 longs), the code is considerably smaller as well (414 vs 913 lines of code), and IMO also simpler. The new code is also much more lightweight. I have measured the speed using artificial xattr-bench benchmark, which spawns P processes, each process sets xattr for F different files, and the value of xattr is randomly chosen from a pool of V values. Averages of runtimes for 5 runs for various combinations of parameters are below. The first value in each cell is old mbache, the second value is the new mbcache. V=10 F\P 1 2 4 8 16 32 64 10 0.158,0.157 0.208,0.196 0.500,0.277 0.798,0.400 3.258,0.584 13.807,1.047 61.339,2.803 100 0.172,0.167 0.279,0.222 0.520,0.275 0.825,0.341 2.981,0.505 12.022,1.202 44.641,2.943 1000 0.185,0.174 0.297,0.239 0.445,0.283 0.767,0.340 2.329,0.480 6.342,1.198 16.440,3.888 V=100 F\P 1 2 4 8 16 32 64 10 0.162,0.153 0.200,0.186 0.362,0.257 0.671,0.496 1.433,0.943 3.801,1.345 7.938,2.501 100 0.153,0.160 0.221,0.199 0.404,0.264 0.945,0.379 1.556,0.485 3.761,1.156 7.901,2.484 1000 0.215,0.191 0.303,0.246 0.471,0.288 0.960,0.347 1.647,0.479 3.916,1.176 8.058,3.160 V=1000 F\P 1 2 4 8 16 32 64 10 0.151,0.129 0.210,0.163 0.326,0.245 0.685,0.521 1.284,0.859 3.087,2.251 6.451,4.801 100 0.154,0.153 0.211,0.191 0.276,0.282 0.687,0.506 1.202,0.877 3.259,1.954 8.738,2.887 1000 0.145,0.179 0.202,0.222 0.449,0.319 0.899,0.333 1.577,0.524 4.221,1.240 9.782,3.579 V=10000 F\P 1 2 4 8 16 32 64 10 0.161,0.154 0.198,0.190 0.296,0.256 0.662,0.480 1.192,0.818 2.989,2.200 6.362,4.746 100 0.176,0.174 0.236,0.203 0.326,0.255 0.696,0.511 1.183,0.855 4.205,3.444 19.510,17.760 1000 0.199,0.183 0.240,0.227 1.159,1.014 2.286,2.154 6.023,6.039 ---,10.933 ---,36.620 V=100000 F\P 1 2 4 8 16 32 64 10 0.171,0.162 0.204,0.198 0.285,0.230 0.692,0.500 1.225,0.881 2.990,2.243 6.379,4.771 100 0.151,0.171 0.220,0.210 0.295,0.255 0.720,0.518 1.226,0.844 3.423,2.831 19.234,17.544 1000 0.192,0.189 0.249,0.225 1.162,1.043 2.257,2.093 5.853,4.997 ---,10.399 ---,32.198 We see that the new code is faster in pretty much all the cases and starting from 4 processes there are significant gains with the new code resulting in upto 20-times shorter runtimes. Also for large numbers of cached entries all values for the old code could not be measured as the kernel started hitting softlockups and died before the test completed. Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- include/linux/mbcache2.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 include/linux/mbcache2.h (limited to 'include/linux') diff --git a/include/linux/mbcache2.h b/include/linux/mbcache2.h new file mode 100644 index 000000000000..b6f160ff2533 --- /dev/null +++ b/include/linux/mbcache2.h @@ -0,0 +1,50 @@ +#ifndef _LINUX_MB2CACHE_H +#define _LINUX_MB2CACHE_H + +#include +#include +#include +#include +#include + +struct mb2_cache; + +struct mb2_cache_entry { + /* LRU list - protected by cache->c_lru_list_lock */ + struct list_head e_lru_list; + /* Hash table list - protected by bitlock in e_hash_list_head */ + struct hlist_bl_node e_hash_list; + atomic_t e_refcnt; + /* Key in hash - stable during lifetime of the entry */ + u32 e_key; + /* Block number of hashed block - stable during lifetime of the entry */ + sector_t e_block; + /* Head of hash list (for list bit lock) - stable */ + struct hlist_bl_head *e_hash_list_head; +}; + +struct mb2_cache *mb2_cache_create(int bucket_bits); +void mb2_cache_destroy(struct mb2_cache *cache); + +int mb2_cache_entry_create(struct mb2_cache *cache, gfp_t mask, u32 key, + sector_t block); +void __mb2_cache_entry_free(struct mb2_cache_entry *entry); +static inline int mb2_cache_entry_put(struct mb2_cache *cache, + struct mb2_cache_entry *entry) +{ + if (!atomic_dec_and_test(&entry->e_refcnt)) + return 0; + __mb2_cache_entry_free(entry); + return 1; +} + +void mb2_cache_entry_delete_block(struct mb2_cache *cache, u32 key, + sector_t block); +struct mb2_cache_entry *mb2_cache_entry_find_first(struct mb2_cache *cache, + u32 key); +struct mb2_cache_entry *mb2_cache_entry_find_next(struct mb2_cache *cache, + struct mb2_cache_entry *entry); +void mb2_cache_entry_touch(struct mb2_cache *cache, + struct mb2_cache_entry *entry); + +#endif /* _LINUX_MB2CACHE_H */ -- cgit v1.2.3 From ecd1e64412d5242b8afdef58a714bab3c5464f79 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 22 Feb 2016 12:21:14 -0500 Subject: mbcache: remove mbcache Both ext2 and ext4 are now converted to mbcache2. Remove the old mbcache code. Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- include/linux/mbcache.h | 55 ------------------------------------------------- 1 file changed, 55 deletions(-) delete mode 100644 include/linux/mbcache.h (limited to 'include/linux') diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h deleted file mode 100644 index 6a392e7a723a..000000000000 --- a/include/linux/mbcache.h +++ /dev/null @@ -1,55 +0,0 @@ -/* - File: linux/mbcache.h - - (C) 2001 by Andreas Gruenbacher, -*/ -struct mb_cache_entry { - struct list_head e_lru_list; - struct mb_cache *e_cache; - unsigned short e_used; - unsigned short e_queued; - atomic_t e_refcnt; - struct block_device *e_bdev; - sector_t e_block; - struct hlist_bl_node e_block_list; - struct { - struct hlist_bl_node o_list; - unsigned int o_key; - } e_index; - struct hlist_bl_head *e_block_hash_p; - struct hlist_bl_head *e_index_hash_p; -}; - -struct mb_cache { - struct list_head c_cache_list; - const char *c_name; - atomic_t c_entry_count; - int c_max_entries; - int c_bucket_bits; - struct kmem_cache *c_entry_cache; - struct hlist_bl_head *c_block_hash; - struct hlist_bl_head *c_index_hash; -}; - -/* Functions on caches */ - -struct mb_cache *mb_cache_create(const char *, int); -void mb_cache_shrink(struct block_device *); -void mb_cache_destroy(struct mb_cache *); - -/* Functions on cache entries */ - -struct mb_cache_entry *mb_cache_entry_alloc(struct mb_cache *, gfp_t); -int mb_cache_entry_insert(struct mb_cache_entry *, struct block_device *, - sector_t, unsigned int); -void mb_cache_entry_release(struct mb_cache_entry *); -void mb_cache_entry_free(struct mb_cache_entry *); -struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *, - struct block_device *, - sector_t); -struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache, - struct block_device *, - unsigned int); -struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache_entry *, - struct block_device *, - unsigned int); -- cgit v1.2.3 From f0c8b46238db9d51ef9ea0858259958d0c601cec Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 22 Feb 2016 18:23:47 -0500 Subject: mbcache2: Use referenced bit instead of LRU Currently we maintain perfect LRU list by moving entry to the tail of the list when it gets used. However these operations on cache-global list are relatively expensive. In this patch we switch to lazy updates of LRU list. Whenever entry gets used, we set a referenced bit in it. When reclaiming entries, we give referenced entries another round in the LRU. Since the list is not a real LRU anymore, rename it to just 'list'. In my testing this logic gives about 30% boost to workloads with mostly unique xattr blocks (e.g. xattr-bench with 10 files and 10000 unique xattr values). Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- include/linux/mbcache2.h | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/mbcache2.h b/include/linux/mbcache2.h index b6f160ff2533..c934843a6a31 100644 --- a/include/linux/mbcache2.h +++ b/include/linux/mbcache2.h @@ -10,8 +10,8 @@ struct mb2_cache; struct mb2_cache_entry { - /* LRU list - protected by cache->c_lru_list_lock */ - struct list_head e_lru_list; + /* List of entries in cache - protected by cache->c_list_lock */ + struct list_head e_list; /* Hash table list - protected by bitlock in e_hash_list_head */ struct hlist_bl_node e_hash_list; atomic_t e_refcnt; @@ -19,8 +19,11 @@ struct mb2_cache_entry { u32 e_key; /* Block number of hashed block - stable during lifetime of the entry */ sector_t e_block; - /* Head of hash list (for list bit lock) - stable */ - struct hlist_bl_head *e_hash_list_head; + /* + * Head of hash list (for list bit lock) - stable. Combined with + * referenced bit of entry + */ + unsigned long _e_hash_list_head; }; struct mb2_cache *mb2_cache_create(int bucket_bits); -- cgit v1.2.3 From 7a2508e1b657cfc7e1371550f88c7a7bc4288f32 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 22 Feb 2016 22:35:22 -0500 Subject: mbcache2: rename to mbcache Since old mbcache code is gone, let's rename new code to mbcache since number 2 is now meaningless. This is just a mechanical replacement. Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- include/linux/mbcache.h | 53 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/mbcache2.h | 53 ------------------------------------------------ 2 files changed, 53 insertions(+), 53 deletions(-) create mode 100644 include/linux/mbcache.h delete mode 100644 include/linux/mbcache2.h (limited to 'include/linux') diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h new file mode 100644 index 000000000000..a74a1f3082fb --- /dev/null +++ b/include/linux/mbcache.h @@ -0,0 +1,53 @@ +#ifndef _LINUX_MBCACHE_H +#define _LINUX_MBCACHE_H + +#include +#include +#include +#include +#include + +struct mb_cache; + +struct mb_cache_entry { + /* List of entries in cache - protected by cache->c_list_lock */ + struct list_head e_list; + /* Hash table list - protected by bitlock in e_hash_list_head */ + struct hlist_bl_node e_hash_list; + atomic_t e_refcnt; + /* Key in hash - stable during lifetime of the entry */ + u32 e_key; + /* Block number of hashed block - stable during lifetime of the entry */ + sector_t e_block; + /* + * Head of hash list (for list bit lock) - stable. Combined with + * referenced bit of entry + */ + unsigned long _e_hash_list_head; +}; + +struct mb_cache *mb_cache_create(int bucket_bits); +void mb_cache_destroy(struct mb_cache *cache); + +int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key, + sector_t block); +void __mb_cache_entry_free(struct mb_cache_entry *entry); +static inline int mb_cache_entry_put(struct mb_cache *cache, + struct mb_cache_entry *entry) +{ + if (!atomic_dec_and_test(&entry->e_refcnt)) + return 0; + __mb_cache_entry_free(entry); + return 1; +} + +void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key, + sector_t block); +struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache, + u32 key); +struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache, + struct mb_cache_entry *entry); +void mb_cache_entry_touch(struct mb_cache *cache, + struct mb_cache_entry *entry); + +#endif /* _LINUX_MBCACHE_H */ diff --git a/include/linux/mbcache2.h b/include/linux/mbcache2.h deleted file mode 100644 index c934843a6a31..000000000000 --- a/include/linux/mbcache2.h +++ /dev/null @@ -1,53 +0,0 @@ -#ifndef _LINUX_MB2CACHE_H -#define _LINUX_MB2CACHE_H - -#include -#include -#include -#include -#include - -struct mb2_cache; - -struct mb2_cache_entry { - /* List of entries in cache - protected by cache->c_list_lock */ - struct list_head e_list; - /* Hash table list - protected by bitlock in e_hash_list_head */ - struct hlist_bl_node e_hash_list; - atomic_t e_refcnt; - /* Key in hash - stable during lifetime of the entry */ - u32 e_key; - /* Block number of hashed block - stable during lifetime of the entry */ - sector_t e_block; - /* - * Head of hash list (for list bit lock) - stable. Combined with - * referenced bit of entry - */ - unsigned long _e_hash_list_head; -}; - -struct mb2_cache *mb2_cache_create(int bucket_bits); -void mb2_cache_destroy(struct mb2_cache *cache); - -int mb2_cache_entry_create(struct mb2_cache *cache, gfp_t mask, u32 key, - sector_t block); -void __mb2_cache_entry_free(struct mb2_cache_entry *entry); -static inline int mb2_cache_entry_put(struct mb2_cache *cache, - struct mb2_cache_entry *entry) -{ - if (!atomic_dec_and_test(&entry->e_refcnt)) - return 0; - __mb2_cache_entry_free(entry); - return 1; -} - -void mb2_cache_entry_delete_block(struct mb2_cache *cache, u32 key, - sector_t block); -struct mb2_cache_entry *mb2_cache_entry_find_first(struct mb2_cache *cache, - u32 key); -struct mb2_cache_entry *mb2_cache_entry_find_next(struct mb2_cache *cache, - struct mb2_cache_entry *entry); -void mb2_cache_entry_touch(struct mb2_cache *cache, - struct mb2_cache_entry *entry); - -#endif /* _LINUX_MB2CACHE_H */ -- cgit v1.2.3 From dc8d5e565f00c9442fa1cbf9acc115475628527c Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Mon, 22 Feb 2016 22:42:05 -0500 Subject: mbcache: get rid of _e_hash_list_head Get rid of field _e_hash_list_head in cache entries and add bit field e_referenced instead. Signed-off-by: Andreas Gruenbacher Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- include/linux/mbcache.h | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) (limited to 'include/linux') diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h index a74a1f3082fb..607e6968542e 100644 --- a/include/linux/mbcache.h +++ b/include/linux/mbcache.h @@ -12,18 +12,14 @@ struct mb_cache; struct mb_cache_entry { /* List of entries in cache - protected by cache->c_list_lock */ struct list_head e_list; - /* Hash table list - protected by bitlock in e_hash_list_head */ + /* Hash table list - protected by hash chain bitlock */ struct hlist_bl_node e_hash_list; atomic_t e_refcnt; /* Key in hash - stable during lifetime of the entry */ u32 e_key; + u32 e_referenced:1; /* Block number of hashed block - stable during lifetime of the entry */ sector_t e_block; - /* - * Head of hash list (for list bit lock) - stable. Combined with - * referenced bit of entry - */ - unsigned long _e_hash_list_head; }; struct mb_cache *mb_cache_create(int bucket_bits); -- cgit v1.2.3 From 6048c64b26097a0ffbd966866b599f990e674e9b Mon Sep 17 00:00:00 2001 From: Andreas Gruenbacher Date: Mon, 22 Feb 2016 22:44:04 -0500 Subject: mbcache: add reusable flag to cache entries To reduce amount of damage caused by single bad block, we limit number of inodes sharing an xattr block to 1024. Thus there can be more xattr blocks with the same contents when there are lots of files with the same extended attributes. These xattr blocks naturally result in hash collisions and can form long hash chains and we unnecessarily check each such block only to find out we cannot use it because it is already shared by too many inodes. Add a reusable flag to cache entries which is cleared when a cache entry has reached its maximum refcount. Cache entries which are not marked reusable are skipped by mb_cache_entry_find_{first,next}. This significantly speeds up mbcache when there are many same xattr blocks. For example for xattr-bench with 5 values and each process handling 20000 files, the run for 64 processes is 25x faster with this patch. Even for 8 processes the speedup is almost 3x. We have also verified that for situations where there is only one xattr block of each kind, the patch doesn't have a measurable cost. [JK: Remove handling of setting the same value since it is not needed anymore, check for races in e_reusable setting, improve changelog, add measurements] Signed-off-by: Andreas Gruenbacher Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- include/linux/mbcache.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h index 607e6968542e..86c9a8b480c5 100644 --- a/include/linux/mbcache.h +++ b/include/linux/mbcache.h @@ -18,6 +18,7 @@ struct mb_cache_entry { /* Key in hash - stable during lifetime of the entry */ u32 e_key; u32 e_referenced:1; + u32 e_reusable:1; /* Block number of hashed block - stable during lifetime of the entry */ sector_t e_block; }; @@ -26,7 +27,7 @@ struct mb_cache *mb_cache_create(int bucket_bits); void mb_cache_destroy(struct mb_cache *cache); int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key, - sector_t block); + sector_t block, bool reusable); void __mb_cache_entry_free(struct mb_cache_entry *entry); static inline int mb_cache_entry_put(struct mb_cache *cache, struct mb_cache_entry *entry) @@ -39,6 +40,8 @@ static inline int mb_cache_entry_put(struct mb_cache *cache, void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key, sector_t block); +struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key, + sector_t block); struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache, u32 key); struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache, -- cgit v1.2.3 From 9bcf976cb8b86eb40e0c0b495a14e4cb967b9c6e Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 22 Feb 2016 23:07:30 -0500 Subject: jbd2: remove unnecessary arguments of jbd2_journal_write_revoke_records jbd2_journal_write_revoke_records() takes journal pointer and write_op, although journal can be obtained from the passed transaction and write_op is always WRITE_SYNC. Remove these superfluous arguments. Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- include/linux/jbd2.h | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 65407f6c9120..5716d9554e77 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -1327,10 +1327,8 @@ extern int jbd2_journal_init_revoke_caches(void); extern void jbd2_journal_destroy_revoke(journal_t *); extern int jbd2_journal_revoke (handle_t *, unsigned long long, struct buffer_head *); extern int jbd2_journal_cancel_revoke(handle_t *, struct journal_head *); -extern void jbd2_journal_write_revoke_records(journal_t *journal, - transaction_t *transaction, - struct list_head *log_bufs, - int write_op); +extern void jbd2_journal_write_revoke_records(transaction_t *transaction, + struct list_head *log_bufs); /* Recovery revoke support */ extern int jbd2_journal_set_revoke(journal_t *, unsigned long long, tid_t); -- cgit v1.2.3 From 32ab671599a89534f37e97d146c27690e371b661 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 22 Feb 2016 23:17:15 -0500 Subject: jbd2: factor out common descriptor block initialization Descriptor block header is initialized in several places. Factor out the common code into jbd2_journal_get_descriptor_buffer(). Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- include/linux/jbd2.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 5716d9554e77..3649cb8d3a41 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -1137,7 +1137,7 @@ static inline void jbd2_unfile_log_bh(struct buffer_head *bh) } /* Log buffer allocation */ -struct buffer_head *jbd2_journal_get_descriptor_buffer(journal_t *journal); +struct buffer_head *jbd2_journal_get_descriptor_buffer(transaction_t *, int); int jbd2_journal_next_log_block(journal_t *, unsigned long long *); int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid, unsigned long *block); -- cgit v1.2.3 From 1101cd4d13ba2f42c5da4c1b9081f35a73b5df31 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 22 Feb 2016 23:19:09 -0500 Subject: jbd2: unify revoke and tag block checksum handling Revoke and tag descriptor blocks are just different kinds of descriptor blocks and thus have checksum in the same place. Unify computation and checking of checksums for these. Reviewed-by: Darrick J. Wong Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o --- include/linux/jbd2.h | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) (limited to 'include/linux') diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 3649cb8d3a41..fd1083c46c61 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -200,7 +200,7 @@ typedef struct journal_block_tag_s __be32 t_blocknr_high; /* most-significant high 32bits. */ } journal_block_tag_t; -/* Tail of descriptor block, for checksumming */ +/* Tail of descriptor or revoke block, for checksumming */ struct jbd2_journal_block_tail { __be32 t_checksum; /* crc32c(uuid+descr_block) */ }; @@ -215,11 +215,6 @@ typedef struct jbd2_journal_revoke_header_s __be32 r_count; /* Count of bytes used in the block */ } jbd2_journal_revoke_header_t; -/* Tail of revoke block, for checksumming */ -struct jbd2_journal_revoke_tail { - __be32 r_checksum; /* crc32c(uuid+revoke_block) */ -}; - /* Definitions for the journal tag flags word: */ #define JBD2_FLAG_ESCAPE 1 /* on-disk block is escaped */ #define JBD2_FLAG_SAME_UUID 2 /* block has same uuid as previous */ @@ -1138,6 +1133,7 @@ static inline void jbd2_unfile_log_bh(struct buffer_head *bh) /* Log buffer allocation */ struct buffer_head *jbd2_journal_get_descriptor_buffer(transaction_t *, int); +void jbd2_descriptor_block_csum_set(journal_t *, struct buffer_head *); int jbd2_journal_next_log_block(journal_t *, unsigned long long *); int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid, unsigned long *block); -- cgit v1.2.3