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Date: Wed, 25 Dec 2013 11:14:05 +0800
From: Robert Yang <liezhi.yang@...driver.com>
To: Robert Yang <liezhi.yang@...driver.com>, <tytso@....edu>,
<dvhart@...ux.intel.com>
CC: <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH V2 09/11] misc/create_inode.c: handle hardlinks
Sorry, this patch should be updated a little, please see my comments inline ...
On 12/24/2013 04:47 PM, Robert Yang wrote:
> Create the inode and save the native inode number when we meet the hard
> link (st_nlink > 1) at the first time, use ext2fs_link() to link the
> name to the target inode number when we meet the same native inode
> number again.
>
> This algorithm is referred this from the genext2fs.
>
> Signed-off-by: Robert Yang <liezhi.yang@...driver.com>
> Reviewed-by: Darren Hart <dvhart@...ux.intel.com>
> ---
> misc/create_inode.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++
> misc/create_inode.h | 18 +++++++++++
> misc/mke2fs.c | 12 +++++++
> 3 files changed, 117 insertions(+)
>
> diff --git a/misc/create_inode.c b/misc/create_inode.c
> index f1af6a9..7462413 100644
> --- a/misc/create_inode.c
> +++ b/misc/create_inode.c
> @@ -10,6 +10,44 @@
> #define S_BLKSIZE 512
> #endif
>
> +/* For saving the hard links */
> +int hdlink_cnt = HDLINK_CNT;
> +
> +/* Link an inode number to a directory */
> +static errcode_t add_link(ext2_ino_t parent_ino, ext2_ino_t ino, const char *name)
> +{
> + struct ext2_inode inode;
> + errcode_t retval;
> +
> + retval = ext2fs_read_inode(current_fs, ino, &inode);
> + if (retval) {
> + com_err(__FUNCTION__, retval, "while reading inode %u", ino);
> + return retval;
> + }
> +
> + retval = ext2fs_link(current_fs, parent_ino, name, ino, inode.i_flags);
> + if (retval == EXT2_ET_DIR_NO_SPACE) {
> + retval = ext2fs_expand_dir(current_fs, parent_ino);
> + if (retval) {
> + com_err(__FUNCTION__, retval, "while expanding directory");
> + return retval;
> + }
> + retval = ext2fs_link(current_fs, parent_ino, name, ino, inode.i_flags);
> + }
> + if (retval) {
> + com_err(__FUNCTION__, retval, "while linking %s", name);
> + return retval;
> + }
> +
> + inode.i_links_count++;
> +
> + retval = ext2fs_write_inode(current_fs, ino, &inode);
> + if (retval)
> + com_err(__FUNCTION__, retval, "while writing inode %u", ino);
> +
> + return retval;
> +}
> +
> /* Fill the uid, gid, mode and time for the inode */
> static void fill_inode(struct ext2_inode *inode, struct stat *st)
> {
> @@ -270,6 +308,17 @@ fail:
> return retval;
> }
>
> +int is_hardlink(ext2_ino_t ino)
> +{
> + int i;
> +
> + for(i = 0; i < hdlinks.count; i++) {
> + if(hdlinks.hdl[i].src_ino == ino)
> + return i;
> + }
> + return -1;
> +}
> +
> /* Copy the native file to the fs */
> errcode_t do_write_internal(ext2_ino_t cwd, const char *src, const char *dest)
> {
> @@ -380,9 +429,11 @@ errcode_t populate_fs(ext2_ino_t parent_ino, const char *source_dir)
> struct dirent *dent;
> struct stat st;
> char ln_target[PATH_MAX];
> + unsigned int save_inode = 0;
The save_inode = 0 should be set before read each file (inside the while
loop), otherwise it will be 1 for other files after we meet the first
hardlink.
// Robert
> ext2_ino_t ino;
> errcode_t retval;
> int read_cnt;
> + int hdlink;
>
> root = EXT2_ROOT_INO;
>
> @@ -404,6 +455,21 @@ errcode_t populate_fs(ext2_ino_t parent_ino, const char *source_dir)
> lstat(dent->d_name, &st);
> name = dent->d_name;
>
> + /* Check for hardlinks */
> + if (!S_ISDIR(st.st_mode) && !S_ISLNK(st.st_mode) && st.st_nlink > 1) {
> + hdlink = is_hardlink(st.st_ino);
> + if (hdlink >= 0) {
> + retval = add_link(parent_ino,
> + hdlinks.hdl[hdlink].dst_ino, name);
> + if (retval) {
> + com_err(__FUNCTION__, retval, "while linking %s", name);
> + return retval;
> + }
> + continue;
> + } else
> + save_inode = 1;
> + }
> +
> switch(st.st_mode & S_IFMT) {
> case S_IFCHR:
> case S_IFBLK:
> @@ -472,6 +538,27 @@ errcode_t populate_fs(ext2_ino_t parent_ino, const char *source_dir)
> _("while setting inode for \"%s\""), name);
> return retval;
> }
> +
> + /* Save the hardlink ino */
> + if (save_inode) {
> + /*
> + * Check whether need more memory, and we don't need
> + * free() since the lifespan will be over after the fs
> + * populated.
> + */
> + if (hdlinks.count == hdlink_cnt) {
> + if ((hdlinks.hdl = realloc (hdlinks.hdl,
> + (hdlink_cnt + HDLINK_CNT) *
> + sizeof (struct hdlink_s))) == NULL) {
> + com_err(name, errno, "Not enough memory");
> + return errno;
> + }
> + hdlink_cnt += HDLINK_CNT;
> + }
> + hdlinks.hdl[hdlinks.count].src_ino = st.st_ino;
> + hdlinks.hdl[hdlinks.count].dst_ino = ino;
> + hdlinks.count++;
> + }
> }
> closedir(dh);
> return retval;
> diff --git a/misc/create_inode.h b/misc/create_inode.h
> index 9fc97fa..2b6d429 100644
> --- a/misc/create_inode.h
> +++ b/misc/create_inode.h
> @@ -6,9 +6,27 @@
> #include "ext2fs/ext2fs.h"
> #include "nls-enable.h"
>
> +struct hdlink_s
> +{
> + ext2_ino_t src_ino;
> + ext2_ino_t dst_ino;
> +};
> +
> +struct hdlinks_s
> +{
> + int count;
> + struct hdlink_s *hdl;
> +};
> +
> +struct hdlinks_s hdlinks;
> +
> ext2_filsys current_fs;
> ext2_ino_t root;
>
> +/* For saving the hard links */
> +#define HDLINK_CNT 4
> +extern int hdlink_cnt;
> +
> /* For populating the filesystem */
> extern errcode_t populate_fs(ext2_ino_t parent_ino, const char *source_dir);
> extern errcode_t do_mknod_internal(ext2_ino_t cwd, const char *name, struct stat *st);
> diff --git a/misc/mke2fs.c b/misc/mke2fs.c
> index eab5463..10cdfd2 100644
> --- a/misc/mke2fs.c
> +++ b/misc/mke2fs.c
> @@ -2802,6 +2802,18 @@ no_journal:
> if (!quiet)
> printf("%s", _("Copying files into the device: "));
>
> + /*
> + * Allocate memory for the hardlinks, we don't need free()
> + * since the lifespan will be over after the fs populated.
> + */
> + if ((hdlinks.hdl = (struct hdlink_s *)
> + malloc(hdlink_cnt * sizeof(struct hdlink_s))) == NULL) {
> + fprintf(stderr, "%s", _("\nNot enough memory\n"));
> + retval = ext2fs_close(fs);
> + return retval;
> + }
> +
> + hdlinks.count = 0;
> current_fs = fs;
> root = EXT2_ROOT_INO;
> retval = populate_fs(root, root_dir);
>
--
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