From 2d9a810729f9c209cab7aa6bf50ec5f749ebff82 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Wed, 27 Nov 2013 01:44:52 +0100

Subject: [PATCH] journal: simplify pre-allocation logic

let's just do a single fallocate() as far as possible, and don't

distuingish between allocated space and file size.

This way we can save a syscall for each append, which makes quite some

benefits.

---

 src/journal/journal-file.c | 19 ++++++++-----------

 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c

index 94e3921..962cdd6 100644

--- a/src/journal/journal-file.c

+++ b/src/journal/journal-file.c

@@ -315,7 +315,7 @@ static int journal_file_verify_header(JournalFile *f) {

 }

 static int journal_file_allocate(JournalFile *f, uint64_t offset, uint64_t size) {

-        uint64_t old_size, new_size, file_size;

+        uint64_t old_size, new_size;

         int r;

         assert(f);

@@ -356,6 +356,11 @@ static int journal_file_allocate(JournalFile *f, uint64_t offset, uint64_t size)

                 }

         }

+        /* Increase by larger blocks at once */

+        new_size = ((new_size+FILE_SIZE_INCREASE-1) / FILE_SIZE_INCREASE) * FILE_SIZE_INCREASE;

+        if (f->metrics.max_size > 0 && new_size > f->metrics.max_size)

+                new_size = f->metrics.max_size;

+

         /* Note that the glibc fallocate() fallback is very

            inefficient, hence we try to minimize the allocation area

            as we can. */

@@ -363,16 +368,8 @@ static int journal_file_allocate(JournalFile *f, uint64_t offset, uint64_t size)

         if (r != 0)

                 return -r;

-        /* Increase the file size a bit further than this, so that we

-         * we can create larger memory maps to cache */

-        file_size = ((new_size+FILE_SIZE_INCREASE-1) / FILE_SIZE_INCREASE) * FILE_SIZE_INCREASE;

-        if (file_size > (uint64_t) f->last_stat.st_size) {

-                if (file_size > new_size)

-                        ftruncate(f->fd, file_size);

-

-                if (fstat(f->fd, &f->last_stat) < 0)

-                        return -errno;

-        }

+        if (fstat(f->fd, &f->last_stat) < 0)

+                return -errno;

         f->header->arena_size = htole64(new_size - le64toh(f->header->header_size));