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From 2d9a810729f9c209cab7aa6bf50ec5f749ebff82 Mon Sep 17 00:00:00 2001
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From: Lennart Poettering <lennart@poettering.net>
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Date: Wed, 27 Nov 2013 01:44:52 +0100
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Subject: [PATCH] journal: simplify pre-allocation logic
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let's just do a single fallocate() as far as possible, and don't
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distuingish between allocated space and file size.
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This way we can save a syscall for each append, which makes quite some
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benefits.
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---
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 src/journal/journal-file.c | 19 ++++++++-----------
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 1 file changed, 8 insertions(+), 11 deletions(-)
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diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
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index 94e3921..962cdd6 100644
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--- a/src/journal/journal-file.c
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+++ b/src/journal/journal-file.c
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@@ -315,7 +315,7 @@ static int journal_file_verify_header(JournalFile *f) {
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 }
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 static int journal_file_allocate(JournalFile *f, uint64_t offset, uint64_t size) {
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-        uint64_t old_size, new_size, file_size;
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+        uint64_t old_size, new_size;
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         int r;
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         assert(f);
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@@ -356,6 +356,11 @@ static int journal_file_allocate(JournalFile *f, uint64_t offset, uint64_t size)
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                 }
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         }
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+        /* Increase by larger blocks at once */
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+        new_size = ((new_size+FILE_SIZE_INCREASE-1) / FILE_SIZE_INCREASE) * FILE_SIZE_INCREASE;
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+        if (f->metrics.max_size > 0 && new_size > f->metrics.max_size)
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+                new_size = f->metrics.max_size;
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+
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         /* Note that the glibc fallocate() fallback is very
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            inefficient, hence we try to minimize the allocation area
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            as we can. */
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@@ -363,16 +368,8 @@ static int journal_file_allocate(JournalFile *f, uint64_t offset, uint64_t size)
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         if (r != 0)
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                 return -r;
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-        /* Increase the file size a bit further than this, so that we
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-         * we can create larger memory maps to cache */
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-        file_size = ((new_size+FILE_SIZE_INCREASE-1) / FILE_SIZE_INCREASE) * FILE_SIZE_INCREASE;
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-        if (file_size > (uint64_t) f->last_stat.st_size) {
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-                if (file_size > new_size)
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-                        ftruncate(f->fd, file_size);
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-
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-                if (fstat(f->fd, &f->last_stat) < 0)
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-                        return -errno;
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-        }
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+        if (fstat(f->fd, &f->last_stat) < 0)
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+                return -errno;
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         f->header->arena_size = htole64(new_size - le64toh(f->header->header_size));
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