From: Robert Yang Subject: Re: [PATCH V2 09/11] misc/create_inode.c: handle hardlinks Date: Wed, 25 Dec 2013 11:14:05 +0800 Message-ID: <52BA4D7D.1020803@windriver.com> References: <1387874847-4922-1-git-send-email-liezhi.yang@windriver.com> <1387874847-4922-10-git-send-email-liezhi.yang@windriver.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Cc: To: Robert Yang , , Return-path: Received: from mail.windriver.com ([147.11.1.11]:46813 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751720Ab3LYDOL (ORCPT ); Tue, 24 Dec 2013 22:14:11 -0500 In-Reply-To: <1387874847-4922-10-git-send-email-liezhi.yang@windriver.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: 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 > Reviewed-by: Darren Hart > --- > 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); >