On Nov 12, 2013, at 11:41 AM, David Howells [off-list ref] wrote:
Add a system call to make extended file stats available, including file
creation time, inode version and data version where available through the
underlying filesystem.
[snip]
The defined bits in st_ioc_flags are the usual FS_xxx_FL, plus some extra flags
that might be supplied by the filesystem. Note that Ext4 returns flags outside
of {EXT4,FS}_FL_USER_VISIBLE in response to FS_IOC_GETFLAGS. Should
{EXT4,FS}_FL_USER_VISIBLE be extended to cover them? Or should the extra flags
be suppressed?
This is a bug in the ext4 code. EXT4_FL_USER_VISIBLE should be extended to cover
all of the flags that are useful to userspace.
quoted hunk
diff --git a/fs/stat.c b/fs/stat.c
index d0ea7ef75e26..a5e603753bd3 100644
--- a/fs/stat.c
+++ b/fs/stat.c
+/**
+ * vfs_fstatx - Get the enhanced basic attributes by file descriptor
+ * @fd: The file descriptor refering to the file of interest
+ * @stat: The result structure to fill in.
+ *
+ * This function is a wrapper around vfs_xgetattr(). The main difference is
+ * that it uses a file descriptor to determine the file location.
+ *
+ * The caller must have preset stat->query_flags, stat->request_mask and
+ * stat->auxinfo as for vfs_xgetattr().
+ *
+ * 0 will be returned on success, and a -ve error code if unsuccessful.
+ */
+int vfs_fstatx(unsigned int fd, struct kstat *stat)
{
struct fd f = fdget_raw(fd);
int error = -EBADF;
if (f.file) {
- error = vfs_getattr(&f.file->f_path, stat);
+ error = vfs_xgetattr(&f.file->f_path, stat);
fdput(f);
}
return error;
}
+EXPORT_SYMBOL(vfs_fstatx);
+
+/**
+ * vfs_fstat - Get basic attributes by file descriptor
+ * @fd: The file descriptor refering to the file of interest
+ * @stat: The result structure to fill in.
+ *
+ * This function is a wrapper around vfs_getattr(). The main difference is
Typo above - vfs_fstat() is a wrapper around vfs_fstatx().
+ * that it uses a file descriptor to determine the file location.
+ *
+ * 0 will be returned on success, and a -ve error code if unsuccessful.
+ */
+int vfs_fstat(unsigned int fd, struct kstat *stat)
+{
+ stat->query_flags = 0;
+ stat->request_mask = STATX_BASIC_STATS;
+ stat->auxinfo = NULL;
+ return vfs_fstatx(fd, stat);
+}
EXPORT_SYMBOL(vfs_fstat);
[snip]
quoted hunk
+/*
+ * Flags to be st_mask
+ *
+ * Query request/result mask for statxat() and struct statx::st_mask.
+ *
+ * These bits should be set in the mask argument of statxat() to request
+ * particular items when calling statxat().
+ */
+#define STATX_MODE 0x00000001U /* Want/got st_mode */
+#define STATX_NLINK 0x00000002U /* Want/got st_nlink */
+#define STATX_UID 0x00000004U /* Want/got st_uid */
+#define STATX_GID 0x00000008U /* Want/got st_gid */
+#define STATX_RDEV 0x00000010U /* Want/got st_rdev */
+#define STATX_ATIME 0x00000020U /* Want/got st_atime */
+#define STATX_MTIME 0x00000040U /* Want/got st_mtime */
+#define STATX_CTIME 0x00000080U /* Want/got st_ctime */
+#define STATX_INO 0x00000100U /* Want/got st_ino */
+#define STATX_SIZE 0x00000200U /* Want/got st_size */
+#define STATX_BLOCKS 0x00000400U /* Want/got st_blocks */
+#define STATX_ALLOC_BLKSIZE 0x00000800U /* Want/got st_alloc_blksize */
+#define STATX_IO_PARAMS 0x00000800U /* Want/got I/O parameters */
+#define STATX_BASIC_STATS 0x00000fffU /* The stuff in the normal stat struct */
Does it make sense for code clarity to #define STATX_BASIC_STATS explicitly in terms
of the symbolic STATX_* fields, instead of just the numeric value?
quoted hunk
+#define STATX_BTIME 0x00001000U /* Want/got st_btime */
+#define STATX_VERSION 0x00002000U /* Want/got st_version */
+#define STATX_IOC_FLAGS 0x00004000U /* Want/got FS_IOC_GETFLAGS */
+#define STATX_ALL_STATS 0x00007fffU /* All supported stats */
This could be #defined in terms of STATX_BASIC_STATS | STATX_{other flags} to make
it easier to see what is in the basic flags, and what is extra.
Cheers, Andreas