diff options
| -rw-r--r-- | fs/file.c | 64 |
1 files changed, 32 insertions, 32 deletions
@@ -60,8 +60,31 @@ static void free_fdtable_rcu(struct rcu_head *rcu) #define BITBIT_SIZE(nr) (BITBIT_NR(nr) * sizeof(long)) /* - * Expand the fdset in the files_struct. Called with the files spinlock - * held for write. + * Copy 'count' fd bits from the old table to the new table and clear the extra + * space if any. This does not copy the file pointers. Called with the files + * spinlock held for write. + */ +static void copy_fd_bitmaps(struct fdtable *nfdt, struct fdtable *ofdt, + unsigned int count) +{ + unsigned int cpy, set; + + cpy = count / BITS_PER_BYTE; + set = (nfdt->max_fds - count) / BITS_PER_BYTE; + memcpy(nfdt->open_fds, ofdt->open_fds, cpy); + memset((char *)nfdt->open_fds + cpy, 0, set); + memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy); + memset((char *)nfdt->close_on_exec + cpy, 0, set); + + cpy = BITBIT_SIZE(count); + set = BITBIT_SIZE(nfdt->max_fds) - cpy; + memcpy(nfdt->full_fds_bits, ofdt->full_fds_bits, cpy); + memset((char *)nfdt->full_fds_bits + cpy, 0, set); +} + +/* + * Copy all file descriptors from the old table to the new, expanded table and + * clear the extra space. Called with the files spinlock held for write. */ static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt) { @@ -72,19 +95,9 @@ static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt) cpy = ofdt->max_fds * sizeof(struct file *); set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *); memcpy(nfdt->fd, ofdt->fd, cpy); - memset((char *)(nfdt->fd) + cpy, 0, set); + memset((char *)nfdt->fd + cpy, 0, set); - cpy = ofdt->max_fds / BITS_PER_BYTE; - set = (nfdt->max_fds - ofdt->max_fds) / BITS_PER_BYTE; - memcpy(nfdt->open_fds, ofdt->open_fds, cpy); - memset((char *)(nfdt->open_fds) + cpy, 0, set); - memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy); - memset((char *)(nfdt->close_on_exec) + cpy, 0, set); - - cpy = BITBIT_SIZE(ofdt->max_fds); - set = BITBIT_SIZE(nfdt->max_fds) - cpy; - memcpy(nfdt->full_fds_bits, ofdt->full_fds_bits, cpy); - memset(cpy+(char *)nfdt->full_fds_bits, 0, set); + copy_fd_bitmaps(nfdt, ofdt, ofdt->max_fds); } static struct fdtable * alloc_fdtable(unsigned int nr) @@ -277,7 +290,7 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) { struct files_struct *newf; struct file **old_fds, **new_fds; - int open_files, size, i; + int open_files, i; struct fdtable *old_fdt, *new_fdt; *errorp = -ENOMEM; @@ -334,13 +347,11 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) open_files = count_open_files(old_fdt); } + copy_fd_bitmaps(new_fdt, old_fdt, open_files); + old_fds = old_fdt->fd; new_fds = new_fdt->fd; - memcpy(new_fdt->open_fds, old_fdt->open_fds, open_files / 8); - memcpy(new_fdt->close_on_exec, old_fdt->close_on_exec, open_files / 8); - memcpy(new_fdt->full_fds_bits, old_fdt->full_fds_bits, BITBIT_SIZE(open_files)); - for (i = open_files; i != 0; i--) { struct file *f = *old_fds++; if (f) { @@ -358,19 +369,8 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) } spin_unlock(&oldf->file_lock); - /* compute the remainder to be cleared */ - size = (new_fdt->max_fds - open_files) * sizeof(struct file *); - - /* This is long word aligned thus could use a optimized version */ - memset(new_fds, 0, size); - - if (new_fdt->max_fds > open_files) { - int left = (new_fdt->max_fds - open_files) / 8; - int start = open_files / BITS_PER_LONG; - - memset(&new_fdt->open_fds[start], 0, left); - memset(&new_fdt->close_on_exec[start], 0, left); - } + /* clear the remainder */ + memset(new_fds, 0, (new_fdt->max_fds - open_files) * sizeof(struct file *)); rcu_assign_pointer(newf->fdt, new_fdt); |
