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files: Cache special file IDs

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We have tons of files with equal IDs, e.g. libraries mapped
to different tasks. No need in writing all this duplicate
stuff into images -- cache the IDs with dev:ino keys.

Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Pavel Emelyanov
2014-02-04 19:32:52 +04:00
parent 3de41b8070
commit 40e4ae9b7b
1 changed files with 63 additions and 1 deletions
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64
file-ids.c
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@@ -6,7 +6,7 @@
#include <unistd.h> #include <unistd.h>
#include <errno.h> #include <errno.h>
#include <string.h> #include <string.h>
#include <sys/stat.h>
#include <sys/types.h> #include <sys/types.h>
#include "asm/types.h" #include "asm/types.h"
@@ -26,9 +26,68 @@ void fd_id_show_tree(void)
kid_show_tree(&fd_tree); kid_show_tree(&fd_tree);
} }
#define FDID_BITS 5
#define FDID_SIZE (1 << FDID_BITS)
#define FDID_MASK (FDID_SIZE - 1)
static inline int fdid_hashfn(unsigned int s_dev, unsigned long i_ino)
{
return (s_dev + i_ino) & FDID_MASK;
}
struct fd_id {
unsigned int dev;
unsigned long ino;
u32 id;
struct fd_id *n;
};
static struct fd_id *fd_id_cache[FDID_SIZE];
static void fd_id_cache_one(u32 id, struct stat *st)
{
struct fd_id *fi;
unsigned hv;
fi = xmalloc(sizeof(*fi));
if (fi) {
fi->dev = st->st_dev;
fi->ino = st->st_ino;
fi->id = id;
hv = fdid_hashfn(st->st_dev, st->st_ino);
fi->n = fd_id_cache[hv];
fd_id_cache[hv] = fi;
}
}
static struct fd_id *fd_id_cache_lookup(struct stat *st)
{
struct fd_id *fi;
for (fi = fd_id_cache[fdid_hashfn(st->st_dev, st->st_ino)];
fi; fi = fi->n)
if (fi->dev == st->st_dev && fi->ino == st->st_ino)
return fi;
return NULL;
}
int fd_id_generate_special(struct stat *st, u32 *id) int fd_id_generate_special(struct stat *st, u32 *id)
{ {
if (st) {
struct fd_id *fi;
fi = fd_id_cache_lookup(st);
if (fi) {
*id = fi->id;
return 0;
}
}
*id = fd_tree.subid++; *id = fd_tree.subid++;
if (st)
fd_id_cache_one(*id, st);
return 1; return 1;
} }
@@ -46,6 +105,9 @@ int fd_id_generate(pid_t pid, FdinfoEntry *fe, struct stat *st)
if (!id) if (!id)
return -ENOMEM; return -ENOMEM;
if (new_id)
fd_id_cache_one(id, st);
fe->id = id; fe->id = id;
return new_id; return new_id;
} }