btrfs-progs: fi du: Calculate space shared by each directory arguments file set
authorMark Fasheh <mfasheh@suse.de>
Wed, 20 Jan 2016 21:49:27 +0000 (13:49 -0800)
committerDavid Sterba <dsterba@suse.com>
Mon, 14 Mar 2016 12:42:47 +0000 (13:42 +0100)
Here we define each file set as those found by a recursive search of a
single directory argument to btrfs fi du.

This isn't as simple as adding up shared extents - they may be shared with
each other, and may also overlap. This patch uses an interval tree to store
shared extents we find while fiemapping files. After collecting them, a 'set
shared' count is calculated by summing (without overlap) each shared region
discovered. This is then displayed to the user as 'set shared'.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>
cmds-fi-du.c

index b413b61..836d357 100644 (file)
 #include "kerncompat.h"
 #include "rbtree.h"
 
+#include "interval_tree_generic.h"
+
 static int summarize = 0;
 static unsigned unit_mode = UNITS_RAW;
 static char path[PATH_MAX] = { 0, };
 static char *pathp = path;
 static char *path_max = &path[PATH_MAX - 1];
 
+struct shared_extent {
+       struct rb_node  rb;
+       u64     start;  /* Start of interval */
+       u64     last;   /* Last location _in_ interval */
+       u64     __subtree_last;
+};
+
+/*
+ * extent_tree_* functions are defined in the massive interval tree
+ * macro below. This serves to illustrate the api in human-readable
+ * terms.
+ */
+static void
+extent_tree_insert(struct shared_extent *node, struct rb_root *root);
+
+static void
+extent_tree_remove(struct shared_extent *node, struct rb_root *root);
+
+static struct shared_extent *
+extent_tree_iter_first(struct rb_root *root,
+                      u64 start, u64 last);
+
+static struct shared_extent *
+extent_tree_iter_next(struct shared_extent *node,
+                       u64 start, u64 last);
+
+#define START(node) ((node)->start)
+#define LAST(node)  ((node)->last)
+
+INTERVAL_TREE_DEFINE(struct shared_extent, rb,
+                    u64, __subtree_last,
+                    START, LAST, static, extent_tree)
+
+static int add_shared_extent(u64 start, u64 len, struct rb_root *root)
+{
+       struct shared_extent *sh;
+
+       BUG_ON(len == 0);
+
+       sh = calloc(1, sizeof(*sh));
+       if (!sh)
+               return ENOMEM;
+
+       sh->start = start;
+       sh->last = (start + len - 1);
+
+       extent_tree_insert(sh, root);
+
+       return 0;
+}
+
+static void cleanup_shared_extents(struct rb_root *root)
+{
+       struct shared_extent *s;
+       struct shared_extent *tmp;
+
+       if (!root)
+               return;
+
+       s = extent_tree_iter_first(root, 0, -1ULL);
+       while (s) {
+               tmp = extent_tree_iter_next(s, 0, -1ULL);
+               extent_tree_remove(s, root);
+
+               free(s);
+               s = tmp;
+       }
+}
+
+#define dprintf(...)
+
+/*
+ * Find all extents which overlap 'n', calculate the space
+ * covered by them and remove those nodes from the tree.
+ */
+static u64 count_unique_bytes(struct rb_root *root, struct shared_extent *n)
+{
+       struct shared_extent *tmp;
+       u64 wstart = n->start;
+       u64 wlast = n->last;
+
+       dprintf("Count overlaps:");
+
+       do {
+               /*
+                * Expand our search window based on the lastest
+                * overlapping extent. Doing this will allow us to
+                * find all possible overlaps
+                */
+               if (wstart > n->start)
+                       wstart = n->start;
+               if (wlast < n->last)
+                       wlast = n->last;
+
+               dprintf(" (%llu, %llu)", n->start, n->last);
+
+               tmp = n;
+               n = extent_tree_iter_next(n, wstart, wlast);
+
+               extent_tree_remove(tmp, root);
+               free(tmp);
+       } while (n);
+
+       dprintf("; wstart: %llu wlast: %llu total: %llu\n", wstart,
+               wlast, wlast - wstart + 1);
+
+       return wlast - wstart + 1;
+}
+
+/*
+ * What we want to do here is get a count of shared bytes within the
+ * set of extents we have collected. Specifcally, we don't want to
+ * count any byte more than once, so just adding them up doesn't
+ * work.
+ *
+ * For each set of overlapping extents we find the lowest start and
+ * highest end. From there we have the actual number of bytes which is
+ * shared across all of the extents in our set. A sum of each sets
+ * extent length is returned.
+ */
+static void count_shared_bytes(struct rb_root *root, u64 *ret_cnt)
+{
+       u64 count = 0;
+       struct shared_extent *s = extent_tree_iter_first(root,
+                                                        0, -1ULL);
+
+       if (!s)
+               goto out;
+
+       while (s) {
+               /*
+                * Find all extents which overlap 's', calculate the space
+                * covered by them and remove those nodes from the tree.
+                */
+               count += count_unique_bytes(root, s);
+
+               /*
+                * Since count_unique_bytes will be emptying the tree,
+                * we can grab the first node here
+                */
+               s = extent_tree_iter_first(root, 0, -1ULL);
+       }
+
+       BUG_ON(!RB_EMPTY_ROOT(root));
+out:
+       *ret_cnt = count;
+}
+
 /* Track which inodes we've seen for the purposes of hardlink detection. */
 struct seen_inode {
        struct rb_node  i_node;
@@ -112,7 +262,21 @@ static int inode_seen(u64 ino, u64 subvol)
                        return EEXIST;
        }
        return 0;
+}
+
+static void clear_seen_inodes(void)
+{
+       struct rb_node *n = rb_first(&seen_inodes);
+       struct seen_inode *si;
 
+       while (n) {
+               si = rb_entry(n, struct seen_inode, i_node);
+
+               rb_erase(&si->i_node, &seen_inodes);
+               free(si);
+
+               n = rb_first(&seen_inodes);
+       }
 }
 
 const char * const cmd_filesystem_du_usage[] = {
@@ -130,7 +294,7 @@ const char * const cmd_filesystem_du_usage[] = {
  * space they will use yet.
  */
 #define        SKIP_FLAGS      (FIEMAP_EXTENT_UNKNOWN|FIEMAP_EXTENT_DELALLOC|FIEMAP_EXTENT_DATA_INLINE)
-static int du_calc_file_space(int dirfd, const char *filename,
+static int du_calc_file_space(int fd, struct rb_root *shared_extents,
                              uint64_t *ret_total, uint64_t *ret_shared)
 {
        char buf[16384];
@@ -142,28 +306,19 @@ static int du_calc_file_space(int dirfd, const char *filename,
        int last = 0;
        int rc;
        u64 ext_len;
-       int fd;
        u64 file_total = 0;
        u64 file_shared = 0;
        u32 flags;
 
        memset(fiemap, 0, sizeof(struct fiemap));
 
-       fd = openat(dirfd, filename, O_RDONLY);
-       if (fd == -1) {
-               ret = errno;
-               fprintf(stderr, "ERROR: can't access '%s': %s\n",
-                       filename, strerror(ret));
-               return ret;
-       }
-
        do {
                fiemap->fm_length = ~0ULL;
                fiemap->fm_extent_count = count;
                rc = ioctl(fd, FS_IOC_FIEMAP, (unsigned long) fiemap);
                if (rc < 0) {
                        ret = errno;
-                       goto out_close;
+                       goto out;
                }
 
                /* If 0 extents are returned, then more ioctls are not needed */
@@ -181,8 +336,17 @@ static int du_calc_file_space(int dirfd, const char *filename,
                                continue;
 
                        file_total += ext_len;
-                       if (flags & FIEMAP_EXTENT_SHARED)
+                       if (flags & FIEMAP_EXTENT_SHARED) {
                                file_shared += ext_len;
+
+                               if (shared_extents) {
+                                       ret = add_shared_extent(fm_ext[i].fe_physical,
+                                                               ext_len,
+                                                               shared_extents);
+                                       if (ret)
+                                               goto out;
+                               }
+                       }
                }
 
                fiemap->fm_start = (fm_ext[i - 1].fe_logical +
@@ -193,28 +357,27 @@ static int du_calc_file_space(int dirfd, const char *filename,
        *ret_shared = file_shared;
 
        ret = 0;
-out_close:
-       close(fd);
+out:
        return ret;
 }
 
 struct du_dir_ctxt {
        uint64_t        bytes_total;
        uint64_t        bytes_shared;
+       DIR             *dirstream;
+       struct rb_root  shared_extents;
 };
+#define INIT_DU_DIR_CTXT       (struct du_dir_ctxt) { 0ULL, 0ULL, NULL, RB_ROOT }
 
-static int du_add_file(const char *filename, int dirfd, uint64_t *ret_total,
+static int du_add_file(const char *filename, int dirfd,
+                      struct rb_root *shared_extents, uint64_t *ret_total,
                       uint64_t *ret_shared, int top_level);
 
-static int du_walk_dir(struct du_dir_ctxt *ctxt)
+static int du_walk_dir(struct du_dir_ctxt *ctxt, struct rb_root *shared_extents)
 {
-       int fd, ret, type;
-       DIR *dirstream = NULL;
+       int ret, type;
        struct dirent *entry;
-
-       fd = open_file_or_dir(path, &dirstream);
-       if (fd < 0)
-               return fd;
+       DIR *dirstream = ctxt->dirstream;
 
        ret = 0;
        do {
@@ -232,8 +395,9 @@ static int du_walk_dir(struct du_dir_ctxt *ctxt)
                                tot = shr = 0;
 
                                ret = du_add_file(entry->d_name,
-                                                 dirfd(dirstream), &tot,
-                                                 &shr, 0);
+                                                 dirfd(dirstream),
+                                                 shared_extents, &tot, &shr,
+                                                 0);
                                if (ret)
                                        break;
 
@@ -243,19 +407,21 @@ static int du_walk_dir(struct du_dir_ctxt *ctxt)
                }
        } while (entry != NULL);
 
-       close_file_or_dir(fd, dirstream);
        return ret;
 }
 
-static int du_add_file(const char *filename, int dirfd, uint64_t *ret_total,
+static int du_add_file(const char *filename, int dirfd,
+                      struct rb_root *shared_extents, uint64_t *ret_total,
                       uint64_t *ret_shared, int top_level)
 {
        int ret, len = strlen(filename);
        char *pathtmp;
        struct stat st;
-       struct du_dir_ctxt dir;
+       struct du_dir_ctxt dir = INIT_DU_DIR_CTXT;
+       int is_dir = 0;
        uint64_t file_total = 0;
        uint64_t file_shared = 0;
+       u64 dir_set_shared = 0;
        u64 subvol;
        int fd;
        DIR *dirstream = NULL;
@@ -300,26 +466,57 @@ static int du_add_file(const char *filename, int dirfd, uint64_t *ret_total,
                goto out_close;
 
        if (S_ISREG(st.st_mode)) {
-               ret = du_calc_file_space(dirfd, filename, &file_total,
+               ret = du_calc_file_space(fd, shared_extents, &file_total,
                                         &file_shared);
                if (ret)
                        goto out_close;
        } else if (S_ISDIR(st.st_mode)) {
-               memset(&dir, 0, sizeof(dir));
+               struct rb_root *root = shared_extents;
+
+               /*
+                * We collect shared extents in an rb_root, the top
+                * level caller will not pass a root down, so use the
+                * one on our dir context.
+                */
+               if (top_level)
+                       root = &dir.shared_extents;
+
+               is_dir = 1;
 
-               ret = du_walk_dir(&dir);
+               dir.dirstream = dirstream;
+               ret = du_walk_dir(&dir, root);
                *pathp = '\0';
-               if (ret)
+               if (ret) {
+                       if (top_level)
+                               cleanup_shared_extents(root);
                        goto out_close;
+               }
 
                file_total = dir.bytes_total;
                file_shared = dir.bytes_shared;
+               if (top_level)
+                       count_shared_bytes(root, &dir_set_shared);
        }
 
        if (!summarize || top_level) {
-               printf("%s\t%s\t%s\n", pretty_size_mode(file_total, unit_mode),
-                      pretty_size_mode((file_total - file_shared), unit_mode),
-                      path);
+               u64 excl = file_total - file_shared;
+
+               if (top_level) {
+                       u64 set_shared = file_shared;
+
+                       if (is_dir)
+                               set_shared = dir_set_shared;
+
+                       printf("%s\t%s\t%s\t%s\n",
+                              pretty_size_mode(file_total, unit_mode),
+                              pretty_size_mode(excl, unit_mode),
+                              pretty_size_mode(set_shared, unit_mode),
+                              path);
+               } else {
+                       printf("%s\t%s\t\t\t%s\n",
+                              pretty_size_mode(file_total, unit_mode),
+                              pretty_size_mode(excl, unit_mode), path);
+               }
        }
 
        if (ret_total)
@@ -369,15 +566,18 @@ int cmd_filesystem_du(int argc, char **argv)
        if (check_argc_min(argc - optind, 1))
                usage(cmd_filesystem_du_usage);
 
-       printf("total\texclusive\tfilename\n");
+       printf("total\texclusive\tset shared\tfilename\n");
 
        for (i = optind; i < argc; i++) {
-               ret = du_add_file(argv[i], AT_FDCWD, NULL, NULL, 1);
+               ret = du_add_file(argv[i], AT_FDCWD, NULL, NULL, NULL, 1);
                if (ret) {
                        fprintf(stderr, "ERROR: can't check space of '%s': %s\n",
                                argv[i], strerror(ret));
                        error = 1;
                }
+
+               /* reset hard-link detection for each argument */
+               clear_seen_inodes();
        }
 
        return error;