statx: Include a mask for stx_attributes in struct statx

Include a mask in struct stat to indicate which bits of stx_attributes the
filesystem actually supports.

This would also be useful if we add another system call that allows you to
do a 'bulk attribute set' and pass in a statx struct with the masks
appropriately set to say what you want to set.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 5d02b922afa31644fd239c77af858d66e7dd5d80..b9ffa9f4191f4cb3a122c215894ef76689fd9604 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5413,6 +5413,12 @@ int ext4_getattr(const struct path *path, struct kstat *stat,
        if (flags & EXT4_NODUMP_FL)
                stat->attributes |= STATX_ATTR_NODUMP;
 
+       stat->attributes_mask |= (STATX_ATTR_APPEND |
+                                 STATX_ATTR_COMPRESSED |
+                                 STATX_ATTR_ENCRYPTED |
+                                 STATX_ATTR_IMMUTABLE |
+                                 STATX_ATTR_NODUMP);
+
        generic_fillattr(inode, stat);
        return 0;
 }

diff --git a/fs/stat.c b/fs/stat.c
index 0c7e6cdc435c2a194dcbdd8684e9c0e9c5f01e6e..c6c963b2546b4f2d0301f40706064498c31fd3b6 100644 (file)
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -527,6 +527,7 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
        tmp.stx_ino = stat->ino;
        tmp.stx_size = stat->size;
        tmp.stx_blocks = stat->blocks;
+       tmp.stx_attributes_mask = stat->attributes_mask;
        tmp.stx_atime.tv_sec = stat->atime.tv_sec;
        tmp.stx_atime.tv_nsec = stat->atime.tv_nsec;
        tmp.stx_btime.tv_sec = stat->btime.tv_sec;

diff --git a/include/linux/stat.h b/include/linux/stat.h
index c76e524fb34b6af362c82103662454750826ac9e..64b6b3aece21aee52a2b7c9246862afb41d606f1 100644 (file)
--- a/include/linux/stat.h
+++ b/include/linux/stat.h
@@ -26,6 +26,7 @@ struct kstat {
        unsigned int    nlink;
        uint32_t        blksize;        /* Preferred I/O size */
        u64             attributes;
+       u64             attributes_mask;
 #define KSTAT_ATTR_FS_IOC_FLAGS                                \
        (STATX_ATTR_COMPRESSED |                        \
         STATX_ATTR_IMMUTABLE |                         \

diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
index 0869b9eaa8ce875fa99e1470daabfa2e4346a189..d538897b8e08bb4358c56148c189fc7b8128a9da 100644 (file)
--- a/include/uapi/linux/stat.h
+++ b/include/uapi/linux/stat.h
@@ -114,7 +114,7 @@ struct statx {
        __u64   stx_ino;        /* Inode number */
        __u64   stx_size;       /* File size */
        __u64   stx_blocks;     /* Number of 512-byte blocks allocated */
-       __u64   __spare1[1];
+       __u64   stx_attributes_mask; /* Mask to show what's supported in stx_attributes */
        /* 0x40 */
        struct statx_timestamp  stx_atime;      /* Last access time */
        struct statx_timestamp  stx_btime;      /* File creation time */
@@ -155,7 +155,7 @@ struct statx {
 #define STATX__RESERVED                0x80000000U     /* Reserved for future struct statx expansion */
 
 /*
- * Attributes to be found in stx_attributes
+ * Attributes to be found in stx_attributes and masked in stx_attributes_mask.
  *
  * These give information about the features or the state of a file that might
  * be of use to ordinary userspace programs such as GUIs or ls rather than

diff --git a/samples/statx/test-statx.c b/samples/statx/test-statx.c
index 8571d766331dd1a513a3f772f3a7ce050909598b..d4d77b09412c416fbe96e648e179a3789347d5ea 100644 (file)
--- a/samples/statx/test-statx.c
+++ b/samples/statx/test-statx.c
@@ -141,8 +141,8 @@ static void dump_statx(struct statx *stx)
        if (stx->stx_mask & STATX_BTIME)
                print_time(" Birth: ", &stx->stx_btime);
 
-       if (stx->stx_attributes) {
-               unsigned char bits;
+       if (stx->stx_attributes_mask) {
+               unsigned char bits, mbits;
                int loop, byte;
 
                static char attr_representation[64 + 1] =
@@ -160,14 +160,18 @@ static void dump_statx(struct statx *stx)
                printf("Attributes: %016llx (", stx->stx_attributes);
                for (byte = 64 - 8; byte >= 0; byte -= 8) {
                        bits = stx->stx_attributes >> byte;
+                       mbits = stx->stx_attributes_mask >> byte;
                        for (loop = 7; loop >= 0; loop--) {
                                int bit = byte + loop;
 
-                               if (bits & 0x80)
+                               if (!(mbits & 0x80))
+                                       putchar('.');   /* Not supported */
+                               else if (bits & 0x80)
                                        putchar(attr_representation[63 - bit]);
                                else
-                                       putchar('-');
+                                       putchar('-');   /* Not set */
                                bits <<= 1;
+                               mbits <<= 1;
                        }
                        if (byte)
                                putchar(' ');