On Nov 20, 2015, at 9:50 AM, Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote: > On 11/20/2015 6:54 AM, David Howells wrote: >> Implement new system calls to provide enhanced file stats and enhanced >> filesystem stats. The patches can be found here: >> >> http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=xstat >> >> >> =========== >> DESCRIPTION >> =========== >> >> The third patch provides this new system call: >> >> long ret = statx(int dfd, >> const char *filename, >> unsigned atflag, >> unsigned mask, >> struct statx *buffer); >> >> This is an enhanced file stat function that provides a number of useful >> features, in summary: >> >> (1) More information: creation time, data version number, >> flags/attributes. A subset of these is available through a number of >> filesystems (such as CIFS, NFS, AFS, Ext4 and BTRFS). >> >> (2) Lightweight stat (AT_NO_ATTR_SYNC): Ask for just those details of >> interest, and allow a network fs to approximate anything not of >> interest, without going to the server. >> >> (3) Heavyweight stat (AT_FORCE_ATTR_SYNC): Force a network fs to flush >> buffers and go to the server, even if it thinks its cached attributes >> are up to date. >> >> (4) Allow the filesystem to indicate what it can/cannot provide: A >> filesystem can now say it doesn't support a standard stat feature if >> that isn't available. >> >> (5) Make the fields a consistent size on all arches, and make them large. >> >> (6) Can be extended by using more request flags and using up the padding >> space in the statx struct. > > How about relevant xattrs? SELinux context, ACL, that sort of thing. > The fact that these are optional should be taken care of by (4). Given that there are a wide variety of xattrs that different apps might be interested in, this would probably be better served by an enhancement to getxattr() or listxattr() to be able to retrieve a whole list of xattrs at once, possibly with some wildcard support (e.g. "security.*") instead of returning all or a specific subset of xattrs with statx() (which is geared toward fixed-size attributes). Cheers, Andreas >> Note that no lstat() equivalent is required as that can be implemented >> through statx() with atflag == 0. There is also no fstat() equivalent as >> that can be implemented through statx() with filename == NULL and the >> relevant fd passed as dfd. >> >> >> The seventh patch provides another new system call: >> >> long ret = fsinfo(int dfd, >> const char *filename, >> unsigned atflag, >> unsigned request, >> void *buffer); >> >> This is an enhanced filesystem stat and information retrieval function that >> provides more information, in summary: >> >> (1) All the information provided by statfs() and more. The fields are >> made large. >> >> (2) Provides information about timestamp range and resolution to >> complement statx(). >> >> (3) Provides information about IOC flags supported in statx()'s return. >> >> (4) Provides volume binary IDs and UUIDs. >> >> (5) Provides the filesystem name according to the kernel as a string >> (eg. "ext4" or "nfs3") in addition to the magic number. >> >> (6) Provides information obtained from network filesystems, such as volume >> and domain names. >> >> (7) Has lots of spare space that can be used for future extenstions and a >> bit mask indicating what was provided. >> >> Note that I've added a 'request' identifier. This is to select the set of >> data to be returned. The idea is that 'buffer' points to a fixed-size >> struct selected by request. Currently only 0 is available and this refers >> to 'struct fsinfo'. However, I could split up the buffer into say 3: >> >> (0) statfs-type information >> >> (1) Timestamp and IOC flags info. >> >> (2) Network fs strings. >> >> However, some of this might be better retrieved through getxattr(). >> >> >> ======= >> TESTING >> ======= >> >> Test programs are added into samples/statx/ by the appropriate patches. >> >> David >> --- >> David Howells (12): >> Ext4: Fix extended timestamp encoding and decoding >> statx: Provide IOC flags for Windows fs attributes >> statx: Add a system call to make enhanced file info available >> statx: AFS: Return enhanced file attributes >> statx: Ext4: Return enhanced file attributes >> statx: NFS: Return enhanced file attributes >> statx: CIFS: Return enhanced attributes >> fsinfo: Add a system call to make enhanced filesystem info available >> fsinfo: Ext4: Return information through the filesystem info syscall >> fsinfo: AFS: Return information through the filesystem info syscall >> fsinfo: NFS: Return information through the filesystem info syscall >> fsinfo: CIFS: Return information through the filesystem info syscall >> >> >> arch/x86/entry/syscalls/syscall_32.tbl | 2 >> arch/x86/entry/syscalls/syscall_64.tbl | 2 >> fs/afs/inode.c | 23 ++ >> fs/afs/super.c | 39 ++++ >> fs/cifs/cifsfs.c | 25 +++ >> fs/cifs/cifsfs.h | 4 >> fs/cifs/cifsglob.h | 8 + >> fs/cifs/dir.c | 2 >> fs/cifs/inode.c | 124 ++++++++++--- >> fs/cifs/netmisc.c | 4 >> fs/exportfs/expfs.c | 4 >> fs/ext4/ext4.h | 24 ++- >> fs/ext4/file.c | 2 >> fs/ext4/inode.c | 31 +++ >> fs/ext4/namei.c | 2 >> fs/ext4/super.c | 39 ++++ >> fs/ext4/symlink.c | 2 >> fs/nfs/inode.c | 45 ++++- >> fs/nfs/internal.h | 1 >> fs/nfs/nfs4super.c | 1 >> fs/nfs/super.c | 58 ++++++ >> fs/ntfs/time.h | 2 >> fs/stat.c | 305 +++++++++++++++++++++++++++++--- >> fs/statfs.c | 218 +++++++++++++++++++++++ >> include/linux/fs.h | 7 + >> include/linux/stat.h | 14 + >> include/linux/syscalls.h | 6 + >> include/linux/time64.h | 2 >> include/uapi/linux/fcntl.h | 2 >> include/uapi/linux/fs.h | 7 + >> include/uapi/linux/stat.h | 185 +++++++++++++++++++ >> samples/Makefile | 3 >> samples/statx/Makefile | 13 + >> samples/statx/test-fsinfo.c | 179 +++++++++++++++++++ >> samples/statx/test-statx.c | 273 +++++++++++++++++++++++++++++ >> 35 files changed, 1558 insertions(+), 100 deletions(-) >> create mode 100644 samples/statx/Makefile >> create mode 100644 samples/statx/test-fsinfo.c >> create mode 100644 samples/statx/test-statx.c >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> Please read the FAQ at http://www.tux.org/lkml/ >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html Cheers, Andreas
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