Welcome! Log In Create A New Profile

Advanced

[nginx] Too large st_blocks values are now ignored (ticket #157).

Maxim Dounin
June 22, 2020 12:20PM
details: https://hg.nginx.org/nginx/rev/52b34c3f89b4
branches:
changeset: 7669:52b34c3f89b4
user: Maxim Dounin <mdounin@mdounin.ru>
date: Mon Jun 22 18:02:59 2020 +0300
description:
Too large st_blocks values are now ignored (ticket #157).

With XFS, using "allocsize=64m" mount option results in large preallocation
being reported in the st_blocks as returned by fstat() till the file is
closed. This in turn results in incorrect cache size calculations and
wrong clearing based on max_size.

To avoid too aggressive cache clearing on such volumes, st_blocks values
which result in sizes larger than st_size and eight blocks (an arbitrary
limit) are no longer trusted, and we use st_size instead.

The ngx_de_fs_size() counterpart is intentionally not modified, as
it is used on closed files and hence not affected by this problem.

diffstat:

src/os/unix/ngx_files.h | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)

diffs (15 lines):

diff -r 0a04e5e4c40b -r 52b34c3f89b4 src/os/unix/ngx_files.h
--- a/src/os/unix/ngx_files.h Mon Jun 22 18:02:58 2020 +0300
+++ b/src/os/unix/ngx_files.h Mon Jun 22 18:02:59 2020 +0300
@@ -185,7 +185,10 @@ ngx_int_t ngx_set_file_time(u_char *name
#define ngx_is_exec(sb) (((sb)->st_mode & S_IXUSR) == S_IXUSR)
#define ngx_file_access(sb) ((sb)->st_mode & 0777)
#define ngx_file_size(sb) (sb)->st_size
-#define ngx_file_fs_size(sb) ngx_max((sb)->st_size, (sb)->st_blocks * 512)
+#define ngx_file_fs_size(sb) \
+ (((sb)->st_blocks * 512 > (sb)->st_size \
+ && (sb)->st_blocks * 512 < (sb)->st_size + 8 * (sb)->st_blksize) \
+ ? (sb)->st_blocks * 512 : (sb)->st_size)
#define ngx_file_mtime(sb) (sb)->st_mtime
#define ngx_file_uniq(sb) (sb)->st_ino

_______________________________________________
nginx-devel mailing list
nginx-devel@nginx.org
http://mailman.nginx.org/mailman/listinfo/nginx-devel
Subject Author Views Posted

[nginx] Too large st_blocks values are now ignored (ticket #157).

Maxim Dounin 64 June 22, 2020 12:20PM



Sorry, you do not have permission to post/reply in this forum.

Online Users

Guests: 308
Record Number of Users: 6 on February 13, 2018
Record Number of Guests: 421 on December 02, 2018
Powered by nginx      Powered by FreeBSD      PHP Powered      Powered by MariaDB      ipv6 ready