Based on kernel commit [1], new flag f_flag is added to statfs struct. Before kernel 2.6.36, glibc's statvfs.f_flags was computed be iterating through all mounted points. This was inefficient and could cause a delay. Since kernel 2.6.36, statfs struct has new field f_flag, which already extracts mount options without iterating through mount point. statfs.f_flag flags of glibc and kernel are the same (plus kernel adds additional flag ST_VALID used only internally). So no matter what version of kernel is used, flags does not change. Flags used in statfs.f_flags can be enumerated from upstreams's glibc/internal_statvfs.c, lines 155-173. Nine flags in sum: ST_RDONLY = 1 ST_NOSUID = 2 ST_NODEV = 4 ST_NOEXEC = 8 ST_SYNCHRONOUS = 16 ST_MANDLOCK = 64 ST_NOATIME = 1024 ST_NODIRATIME = 2048 ST_RELATIME = 4096 This patch describes missing flag. [1] https://github.com/torvalds/linux/commit/365b18189789bfa1acd9939e6312b8a4b4577b28 Signed-off-by: Jan Chaloupka <jchaloup@xxxxxxxxxx> --- man2/statfs.2 | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff --git a/man2/statfs.2 b/man2/statfs.2 index 714bc7c..46cfa5f 100644 --- a/man2/statfs.2 +++ b/man2/statfs.2 @@ -65,7 +65,9 @@ struct statfs { fsid_t f_fsid; /* filesystem id */ __SWORD_TYPE f_namelen; /* maximum length of filenames */ __SWORD_TYPE f_frsize; /* fragment size (since Linux 2.6) */ - __SWORD_TYPE f_spare[5]; + __SWORD_TYPE f_flags; /* mount flags of filesystem + (since Linux 2.6.36) */ + __SWORD_TYPE f_spare[4]; }; Filesystem types: @@ -146,6 +148,30 @@ Most of these MAGIC constants are defined in .IR /usr/include/linux/magic.h , and some are hardcoded in kernel sources. .PP +Mount flags of +.I f_flags +field are extracted from an option string of a mount point defined in +.BR mount (8). +The field can be combination of the following flags +(corresponding mount options are in the right column): +.in +.nf + + ST_RDONLY ro + ST_NOSUID nosuid + ST_NOEXEC noexec + ST_NODEV nodev + ST_SYNCHRONOUS sync + ST_MANDLOCK mand + ST_NOATIME noatime + ST_NODIRATIME nodiratime + ST_RELATIME relatime + +.fi +.in +For kernel less than 2.6.36 option flags are extracted by iterating +through individual mount points which can be inefficient and cause delay. +.PP Nobody knows what .I f_fsid is supposed to contain (but see below). -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
