jbd2: Reserve space for revoke descriptor blocks

Extend functions for starting, extending, and restarting transaction
handles to take number of revoke records handle must be able to
accommodate. These functions then make sure transaction has enough
credits to be able to store resulting revoke descriptor blocks. Also
revoke code tracks number of revoke records created by a handle to catch
situation where some place didn't reserve enough space for revoke
records. Similarly to standard transaction credits, space for unused
reserved revoke records is released when the handle is stopped.

On the ext4 side we currently take a simplistic approach of reserving
space for 1024 revoke records for any transaction. This grows amount of
credits reserved for each handle only by a few and is enough for any
normal workload so that we don't hit warnings in jbd2. We will refine
the logic in following commits.

Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20191105164437.32602-20-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index 731bbfdbce5b9ee8e22c53389d32cac8a8eb81d1..b81190bee32d6e16229dff1566e80e9fc746eb77 100644 (file)
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -78,7 +78,7 @@ handle_t *__ext4_journal_start_sb(struct super_block *sb, unsigned int line,
        journal = EXT4_SB(sb)->s_journal;
        if (!journal)
                return ext4_get_nojournal();
-       return jbd2__journal_start(journal, blocks, rsv_blocks, GFP_NOFS,
+       return jbd2__journal_start(journal, blocks, rsv_blocks, 1024, GFP_NOFS,
                                   type, line);
 }
 

diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 36aa725996468e194e2bc64e5f83ce7a8f4a9263..aca05e52e3170a4fa7a5678ed4f38d56b907df34 100644 (file)
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -328,14 +328,14 @@ static inline handle_t *ext4_journal_current_handle(void)
 static inline int ext4_journal_extend(handle_t *handle, int nblocks)
 {
        if (ext4_handle_valid(handle))
-               return jbd2_journal_extend(handle, nblocks);
+               return jbd2_journal_extend(handle, nblocks, 1024);
        return 0;
 }
 
 static inline int ext4_journal_restart(handle_t *handle, int nblocks)
 {
        if (ext4_handle_valid(handle))
-               return jbd2_journal_restart(handle, nblocks);
+               return jbd2__journal_restart(handle, nblocks, 1024, GFP_NOFS);
        return 0;
 }
 

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 22b14b3ca197c09ff42658b0ef3b7fd38159c836..eef809f617227eb5985452c35a98cd9bb86ae2ca 100644 (file)
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1500,6 +1500,21 @@ void jbd2_journal_update_sb_errno(journal_t *journal)
 }
 EXPORT_SYMBOL(jbd2_journal_update_sb_errno);
 
+static int journal_revoke_records_per_block(journal_t *journal)
+{
+       int record_size;
+       int space = journal->j_blocksize - sizeof(jbd2_journal_revoke_header_t);
+
+       if (jbd2_has_feature_64bit(journal))
+               record_size = 8;
+       else
+               record_size = 4;
+
+       if (jbd2_journal_has_csum_v2or3(journal))
+               space -= sizeof(struct jbd2_journal_block_tail);
+       return space / record_size;
+}
+
 /*
  * Read the superblock for a given journal, performing initial
  * validation of the format.
@@ -1608,6 +1623,8 @@ static int journal_get_superblock(journal_t *journal)
                                                   sizeof(sb->s_uuid));
        }
 
+       journal->j_revoke_records_per_block =
+                               journal_revoke_records_per_block(journal);
        set_buffer_verified(bh);
 
        return 0;
@@ -1928,6 +1945,8 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
        sb->s_feature_ro_compat |= cpu_to_be32(ro);
        sb->s_feature_incompat  |= cpu_to_be32(incompat);
        unlock_buffer(journal->j_sb_buffer);
+       journal->j_revoke_records_per_block =
+                               journal_revoke_records_per_block(journal);
 
        return 1;
 #undef COMPAT_FEATURE_ON
@@ -1958,6 +1977,8 @@ void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
        sb->s_feature_compat    &= ~cpu_to_be32(compat);
        sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
        sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
+       journal->j_revoke_records_per_block =
+                               journal_revoke_records_per_block(journal);
 }
 EXPORT_SYMBOL(jbd2_journal_clear_features);
 

diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c
index f08073d7bbf57d975a1f85957b39ef497f1a38aa..fa608788b93d7c55977b8c64201374ffb6a1a42c 100644 (file)
--- a/fs/jbd2/revoke.c
+++ b/fs/jbd2/revoke.c
@@ -371,6 +371,11 @@ int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
        }
 #endif
 
+       if (WARN_ON_ONCE(handle->h_revoke_credits <= 0)) {
+               if (!bh_in)
+                       brelse(bh);
+               return -EIO;
+       }
        /* We really ought not ever to revoke twice in a row without
            first having the revoke cancelled: it's illegal to free a
            block twice without allocating it in between! */
@@ -391,6 +396,7 @@ int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
                        __brelse(bh);
                }
        }
+       handle->h_revoke_credits--;
 
        jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
        err = insert_revoke_hash(journal, blocknr,

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index ba388da7e02bd24bc7b3eca0ea4de6699fd984e0..1c121afbcf8f900753186bdd5bc10f001af35d51 100644 (file)
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -101,6 +101,7 @@ static void jbd2_get_transaction(journal_t *journal,
        atomic_set(&transaction->t_outstanding_credits,
                   jbd2_descriptor_blocks_per_trans(journal) +
                   atomic_read(&journal->j_reserved_credits));
+       atomic_set(&transaction->t_outstanding_revokes, 0);
        atomic_set(&transaction->t_handle_count, 0);
        INIT_LIST_HEAD(&transaction->t_inode_list);
        INIT_LIST_HEAD(&transaction->t_private_list);
@@ -418,6 +419,7 @@ repeat:
        update_t_max_wait(transaction, ts);
        handle->h_transaction = transaction;
        handle->h_requested_credits = blocks;
+       handle->h_revoke_credits_requested = handle->h_revoke_credits;
        handle->h_start_jiffies = jiffies;
        atomic_inc(&transaction->t_updates);
        atomic_inc(&transaction->t_handle_count);
@@ -451,8 +453,8 @@ static handle_t *new_handle(int nblocks)
 }
 
 handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks,
-                             gfp_t gfp_mask, unsigned int type,
-                             unsigned int line_no)
+                             int revoke_records, gfp_t gfp_mask,
+                             unsigned int type, unsigned int line_no)
 {
        handle_t *handle = journal_current_handle();
        int err;
@@ -466,6 +468,8 @@ handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks,
                return handle;
        }
 
+       nblocks += DIV_ROUND_UP(revoke_records,
+                               journal->j_revoke_records_per_block);
        handle = new_handle(nblocks);
        if (!handle)
                return ERR_PTR(-ENOMEM);
@@ -481,6 +485,7 @@ handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks,
                rsv_handle->h_journal = journal;
                handle->h_rsv_handle = rsv_handle;
        }
+       handle->h_revoke_credits = revoke_records;
 
        err = start_this_handle(journal, handle, gfp_mask);
        if (err < 0) {
@@ -521,7 +526,7 @@ EXPORT_SYMBOL(jbd2__journal_start);
  */
 handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
 {
-       return jbd2__journal_start(journal, nblocks, 0, GFP_NOFS, 0, 0);
+       return jbd2__journal_start(journal, nblocks, 0, 0, GFP_NOFS, 0, 0);
 }
 EXPORT_SYMBOL(jbd2_journal_start);
 
@@ -598,6 +603,7 @@ EXPORT_SYMBOL(jbd2_journal_start_reserved);
  * int jbd2_journal_extend() - extend buffer credits.
  * @handle:  handle to 'extend'
  * @nblocks: nr blocks to try to extend by.
+ * @revoke_records: number of revoke records to try to extend by.
  *
  * Some transactions, such as large extends and truncates, can be done
  * atomically all at once or in several stages.  The operation requests
@@ -614,7 +620,7 @@ EXPORT_SYMBOL(jbd2_journal_start_reserved);
  * return code < 0 implies an error
  * return code > 0 implies normal transaction-full status.
  */
-int jbd2_journal_extend(handle_t *handle, int nblocks)
+int jbd2_journal_extend(handle_t *handle, int nblocks, int revoke_records)
 {
        transaction_t *transaction = handle->h_transaction;
        journal_t *journal;
@@ -636,6 +642,12 @@ int jbd2_journal_extend(handle_t *handle, int nblocks)
                goto error_out;
        }
 
+       nblocks += DIV_ROUND_UP(
+                       handle->h_revoke_credits_requested + revoke_records,
+                       journal->j_revoke_records_per_block) -
+               DIV_ROUND_UP(
+                       handle->h_revoke_credits_requested,
+                       journal->j_revoke_records_per_block);
        spin_lock(&transaction->t_handle_lock);
        wanted = atomic_add_return(nblocks,
                                   &transaction->t_outstanding_credits);
@@ -655,6 +667,8 @@ int jbd2_journal_extend(handle_t *handle, int nblocks)
 
        handle->h_buffer_credits += nblocks;
        handle->h_requested_credits += nblocks;
+       handle->h_revoke_credits += revoke_records;
+       handle->h_revoke_credits_requested += revoke_records;
        result = 0;
 
        jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
@@ -669,10 +683,31 @@ static void stop_this_handle(handle_t *handle)
 {
        transaction_t *transaction = handle->h_transaction;
        journal_t *journal = transaction->t_journal;
+       int revokes;
 
        J_ASSERT(journal_current_handle() == handle);
        J_ASSERT(atomic_read(&transaction->t_updates) > 0);
        current->journal_info = NULL;
+       /*
+        * Subtract necessary revoke descriptor blocks from handle credits. We
+        * take care to account only for revoke descriptor blocks the
+        * transaction will really need as large sequences of transactions with
+        * small numbers of revokes are relatively common.
+        */
+       revokes = handle->h_revoke_credits_requested - handle->h_revoke_credits;
+       if (revokes) {
+               int t_revokes, revoke_descriptors;
+               int rr_per_blk = journal->j_revoke_records_per_block;
+
+               WARN_ON_ONCE(DIV_ROUND_UP(revokes, rr_per_blk)
+                               > handle->h_buffer_credits);
+               t_revokes = atomic_add_return(revokes,
+                               &transaction->t_outstanding_revokes);
+               revoke_descriptors =
+                       DIV_ROUND_UP(t_revokes, rr_per_blk) -
+                       DIV_ROUND_UP(t_revokes - revokes, rr_per_blk);
+               handle->h_buffer_credits -= revoke_descriptors;
+       }
        atomic_sub(handle->h_buffer_credits,
                   &transaction->t_outstanding_credits);
        if (handle->h_rsv_handle)
@@ -692,6 +727,7 @@ static void stop_this_handle(handle_t *handle)
  * int jbd2_journal_restart() - restart a handle .
  * @handle:  handle to restart
  * @nblocks: nr credits requested
+ * @revoke_records: number of revoke record credits requested
  * @gfp_mask: memory allocation flags (for start_this_handle)
  *
  * Restart a handle for a multi-transaction filesystem
@@ -704,7 +740,8 @@ static void stop_this_handle(handle_t *handle)
  * credits. We preserve reserved handle if there's any attached to the
  * passed in handle.
  */
-int jbd2__journal_restart(handle_t *handle, int nblocks, gfp_t gfp_mask)
+int jbd2__journal_restart(handle_t *handle, int nblocks, int revoke_records,
+                         gfp_t gfp_mask)
 {
        transaction_t *transaction = handle->h_transaction;
        journal_t *journal;
@@ -735,7 +772,10 @@ int jbd2__journal_restart(handle_t *handle, int nblocks, gfp_t gfp_mask)
        read_unlock(&journal->j_state_lock);
        if (need_to_start)
                jbd2_log_start_commit(journal, tid);
-       handle->h_buffer_credits = nblocks;
+       handle->h_buffer_credits = nblocks +
+               DIV_ROUND_UP(revoke_records,
+                            journal->j_revoke_records_per_block);
+       handle->h_revoke_credits = revoke_records;
        return start_this_handle(journal, handle, gfp_mask);
 }
 EXPORT_SYMBOL(jbd2__journal_restart);
@@ -743,7 +783,7 @@ EXPORT_SYMBOL(jbd2__journal_restart);
 
 int jbd2_journal_restart(handle_t *handle, int nblocks)
 {
-       return jbd2__journal_restart(handle, nblocks, GFP_NOFS);
+       return jbd2__journal_restart(handle, nblocks, 0, GFP_NOFS);
 }
 EXPORT_SYMBOL(jbd2_journal_restart);
 

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 019aaf2a3f8aebd8e99faa234b50142a34cb5aca..a032f0297dad167a4f14f659aedd2d05bd23560a 100644 (file)
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -426,7 +426,7 @@ int ocfs2_extend_trans(handle_t *handle, int nblocks)
 #ifdef CONFIG_OCFS2_DEBUG_FS
        status = 1;
 #else
-       status = jbd2_journal_extend(handle, nblocks);
+       status = jbd2_journal_extend(handle, nblocks, 0);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
@@ -466,7 +466,7 @@ int ocfs2_allocate_extend_trans(handle_t *handle, int thresh)
        if (old_nblks < thresh)
                return 0;
 
-       status = jbd2_journal_extend(handle, OCFS2_MAX_TRANS_DATA);
+       status = jbd2_journal_extend(handle, OCFS2_MAX_TRANS_DATA, 0);
        if (status < 0) {
                mlog_errno(status);
                goto bail;

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 1dd2703a8e26495c3b3b2d0e1afaca0daa9a2040..2a3d5f50e7a1d07939cc6b9d34c032a5fb2d332e 100644 (file)
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -478,6 +478,7 @@ struct jbd2_revoke_table_s;
  * @h_journal: Which journal handle belongs to - used iff h_reserved set.
  * @h_rsv_handle: Handle reserved for finishing the logical operation.
  * @h_buffer_credits: Number of remaining buffers we are allowed to dirty.
+ * @h_revoke_credits: Number of remaining revoke records available for handle
  * @h_ref: Reference count on this handle.
  * @h_err: Field for caller's use to track errors through large fs operations.
  * @h_sync: Flag for sync-on-close.
@@ -488,6 +489,7 @@ struct jbd2_revoke_table_s;
  * @h_line_no: For handle statistics.
  * @h_start_jiffies: Handle Start time.
  * @h_requested_credits: Holds @h_buffer_credits after handle is started.
+ * @h_revoke_credits_requested: Holds @h_revoke_credits after handle is started.
  * @saved_alloc_context: Saved context while transaction is open.
  **/
 
@@ -505,6 +507,8 @@ struct jbd2_journal_handle
 
        handle_t                *h_rsv_handle;
        int                     h_buffer_credits;
+       int                     h_revoke_credits;
+       int                     h_revoke_credits_requested;
        int                     h_ref;
        int                     h_err;
 
@@ -688,6 +692,17 @@ struct transaction_s
         */
        atomic_t                t_outstanding_credits;
 
+       /*
+        * Number of revoke records for this transaction added by already
+        * stopped handles. [none]
+        */
+       atomic_t                t_outstanding_revokes;
+
+       /*
+        * How many handles used this transaction? [none]
+        */
+       atomic_t                t_handle_count;
+
        /*
         * Forward and backward links for the circular list of all transactions
         * awaiting checkpoint. [j_list_lock]
@@ -705,11 +720,6 @@ struct transaction_s
         */
        ktime_t                 t_start_time;
 
-       /*
-        * How many handles used this transaction? [none]
-        */
-       atomic_t                t_handle_count;
-
        /*
         * This transaction is being forced and some process is
         * waiting for it to finish.
@@ -1026,6 +1036,13 @@ struct journal_s
         */
        int                     j_max_transaction_buffers;
 
+       /**
+        * @j_revoke_records_per_block:
+        *
+        * Number of revoke records that fit in one descriptor block.
+        */
+       int                     j_revoke_records_per_block;
+
        /**
         * @j_commit_interval:
         *
@@ -1360,14 +1377,16 @@ static inline handle_t *journal_current_handle(void)
 
 extern handle_t *jbd2_journal_start(journal_t *, int nblocks);
 extern handle_t *jbd2__journal_start(journal_t *, int blocks, int rsv_blocks,
-                                    gfp_t gfp_mask, unsigned int type,
-                                    unsigned int line_no);
+                                    int revoke_records, gfp_t gfp_mask,
+                                    unsigned int type, unsigned int line_no);
 extern int      jbd2_journal_restart(handle_t *, int nblocks);
-extern int      jbd2__journal_restart(handle_t *, int nblocks, gfp_t gfp_mask);
+extern int      jbd2__journal_restart(handle_t *, int nblocks,
+                                      int revoke_records, gfp_t gfp_mask);
 extern int      jbd2_journal_start_reserved(handle_t *handle,
                                unsigned int type, unsigned int line_no);
 extern void     jbd2_journal_free_reserved(handle_t *handle);
-extern int      jbd2_journal_extend (handle_t *, int nblocks);
+extern int      jbd2_journal_extend(handle_t *handle, int nblocks,
+                                    int revoke_records);
 extern int      jbd2_journal_get_write_access(handle_t *, struct buffer_head *);
 extern int      jbd2_journal_get_create_access (handle_t *, struct buffer_head *);
 extern int      jbd2_journal_get_undo_access(handle_t *, struct buffer_head *);
@@ -1631,7 +1650,11 @@ static inline tid_t  jbd2_get_latest_transaction(journal_t *journal)
 
 static inline int jbd2_handle_buffer_credits(handle_t *handle)
 {
-       return handle->h_buffer_credits;
+       journal_t *journal = handle->h_transaction->t_journal;
+
+       return handle->h_buffer_credits -
+               DIV_ROUND_UP(handle->h_revoke_credits_requested,
+                            journal->j_revoke_records_per_block);
 }
 
 #ifdef __KERNEL__