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Message-ID: <5136B457.1060805@tao.ma>
Date: Wed, 06 Mar 2013 11:13:27 +0800
From: Tao Ma <tm@....ma>
To: Andrey Borzenkov <arvidjaar@...il.com>
CC: grub-devel@....org, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] add ext4 inode inline data support to grub2
Hi Andrey,
Thanks for the effort.
On 03/06/2013 02:30 AM, Andrey Borzenkov wrote:
> Add support for reading inode inline data as supported by ext4
> as of linux kernel 3.8.
>
> grub_ext2_inode_read() - read full inode (not only minimal compatible
> ext2 part) and use it to search for inline data. Additionally it
> saves inode block and offset for later use in grub_ext2_file_read for
> inline data.
>
> grub_ext2_find_inline_data() - search for extended attribute "data" in
> system namespace. if present, inode has inline data. Calculate offset
> and store it and size. Non-zero offset is used as flag that inline data
> is present.
>
> grub_ext2_file_read() - if inode has inline data, it is stored in up
> to two chunks - in place of block pointers and in available space after
> inode proper. It uses standard grub_disk_read() so all hooks are called
> if present.
>
> To actually create inline data EXT4_FEATURE_INCOMPAT_INLINE_DATA must
> be present in superblock. As of today e2fsprogs refuse to touch filesystem
> if this flag is present; the only way to set it is to use debugfs
> directly.
I guess you can use the dev branch of e2fsprogs.git so that mkfs can
build an inline data enabled volume for you? That test would be more
realistic. :)
Anyway, the codes look good to me.
Thanks,
Tao
>
> Patch was lightly tested using grub-fstest on a ext4 image created under
> 3.8 with EXT4_FEATURE_INCOMPAT_INLINE_DATA set using debugfs. Tested were
> inline files, inline directories and inline symlinks.
>
> Signed-off-by: Andrey Borzenkov <arvidjaar@...il.com>
>
> ---
> grub-core/fs/ext2.c | 255 ++++++++++++++++++++++++++++++++++++++++++---------
> 1 file changed, 214 insertions(+), 41 deletions(-)
>
> diff --git a/grub-core/fs/ext2.c b/grub-core/fs/ext2.c
> index 18429ac..7304891 100644
> --- a/grub-core/fs/ext2.c
> +++ b/grub-core/fs/ext2.c
> @@ -89,6 +89,9 @@ GRUB_MOD_LICENSE ("GPLv3+");
> #define EXT4_FEATURE_RO_COMPAT_GDT_CSUM 0x0010
> #define EXT4_FEATURE_RO_COMPAT_DIR_NLINK 0x0020
> #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE 0x0040
> +#define EXT4_FEATURE_RO_COMPAT_QUOTA 0x0100
> +#define EXT4_FEATURE_RO_COMPAT_BIGALLOC 0x0200
> +#define EXT4_FEATURE_RO_COMPAT_METADATA_CSUM 0x0400
> /* Superblock filesystem feature flags (back-incompatible)
> * A filesystem with any of these enabled should not be attempted to be read
> * by a driver that does not understand them, since they usually indicate
> @@ -101,13 +104,19 @@ GRUB_MOD_LICENSE ("GPLv3+");
> #define EXT4_FEATURE_INCOMPAT_EXTENTS 0x0040 /* Extents used */
> #define EXT4_FEATURE_INCOMPAT_64BIT 0x0080
> #define EXT4_FEATURE_INCOMPAT_FLEX_BG 0x0200
> +#define EXT4_FEATURE_INCOMPAT_EA_INODE 0x0400 /* EA in inode */
> +#define EXT4_FEATURE_INCOMPAT_DIRDATA 0x1000 /* data in dirent */
> +#define EXT4_FEATURE_INCOMPAT_BG_USE_META_CSUM 0x2000 /* use crc32c for bg */
> +#define EXT4_FEATURE_INCOMPAT_LARGEDIR 0x4000 /* >2GB or 3-lvl htree */
> +#define EXT4_FEATURE_INCOMPAT_INLINE_DATA 0x8000 /* data in inode */
>
> /* The set of back-incompatible features this driver DOES support. Add (OR)
> * flags here as the related features are implemented into the driver. */
> #define EXT2_DRIVER_SUPPORTED_INCOMPAT ( EXT2_FEATURE_INCOMPAT_FILETYPE \
> | EXT4_FEATURE_INCOMPAT_EXTENTS \
> | EXT4_FEATURE_INCOMPAT_FLEX_BG \
> - | EXT4_FEATURE_INCOMPAT_64BIT)
> + | EXT4_FEATURE_INCOMPAT_64BIT \
> + | EXT4_FEATURE_INCOMPAT_INLINE_DATA)
> /* List of rationales for the ignored "incompatible" features:
> * needs_recovery: Not really back-incompatible - was added as such to forbid
> * ext2 drivers from mounting an ext3 volume with a dirty
> @@ -308,12 +317,40 @@ struct grub_ext4_extent_idx
> grub_uint16_t unused;
> };
>
> +#define EXT4_XATTR_MAGIC 0xEA020000
> +#define EXT4_XATTR_INDEX_SYSTEM 7
> +#define EXT4_XATTR_SYSTEM_DATA "data"
> +#define EXT4_INLINE_DOTDOT_SIZE 4
> +
> +struct grub_ext4_xattr_entry
> +{
> + grub_uint8_t name_len; /* length of name */
> + grub_uint8_t name_index; /* attribute name index */
> + grub_uint16_t value_offs; /* offset in disk block of value */
> + grub_uint32_t value_block; /* disk block attribute is stored on */
> + grub_uint32_t value_size; /* size of attribute value */
> + grub_uint32_t hash; /* hash value of name and value */
> + char name[0]; /* attribute name */
> +};
> +
> +#define EXT4_XATTR_LEN(name_len) \
> + (((name_len) + sizeof(struct grub_ext4_xattr_entry) + 3) & ~3)
> +#define EXT4_XATTR_NEXT(entry) \
> + ((struct grub_ext4_xattr_entry *)( \
> + (char *)(entry) + EXT4_XATTR_LEN((entry)->name_len)))
> +#define IS_LAST_ENTRY(entry) (*(grub_uint32_t *)(entry) == 0)
> +
> +
> struct grub_fshelp_node
> {
> struct grub_ext2_data *data;
> struct grub_ext2_inode inode;
> int ino;
> int inode_read;
> + grub_disk_addr_t inode_base; /* Inode filesystem block */
> + grub_off_t inode_offs; /* Inode offset in filesystem block */
> + grub_off_t inline_offs; /* Offset of inline data from start of inode */
> + grub_size_t inline_size; /* Size of inline data */
> };
>
> /* Information about a "mounted" ext2 filesystem. */
> @@ -330,6 +367,61 @@ static grub_dl_t my_mod;
>
> .
>
> +/* Inline data is stored using inline extended attributes. Attributes consist
> + of entry and value. Entries start after inode proper, following 4 bytes
> + magic header. Each entry is 4 bytes aligned, end of list is marked with
> + 4 bytes zero. Values are stored after entries.
> +
> + Inline data is stored as system attribute with name "data". First part of
> + data is kept in space reserved for block pointers, so it is valid for value
> + size to be zero. Offset is apparently non-zero even in this case.
> + */
> +inline static void
> +grub_ext2_find_inline_data (struct grub_fshelp_node *node, grub_size_t isize, grub_uint8_t *inode)
> +{
> + grub_size_t extra;
> + grub_uint32_t *ihdr;
> + struct grub_ext4_xattr_entry *entry;
> + grub_uint8_t *iend = inode + isize - sizeof (grub_uint32_t);
> +
> + node->inline_offs = 0;
> +
> + if (isize < EXT2_GOOD_OLD_INODE_SIZE + sizeof (grub_uint16_t))
> + return;
> + extra = grub_le_to_cpu16 (*(grub_uint16_t *)(inode + EXT2_GOOD_OLD_INODE_SIZE));
> + if (EXT2_GOOD_OLD_INODE_SIZE + extra + sizeof (*ihdr) > isize)
> + return;
> + ihdr = (grub_uint32_t *)(inode + EXT2_GOOD_OLD_INODE_SIZE + extra);
> + if (*ihdr != grub_cpu_to_le32_compile_time (EXT4_XATTR_MAGIC))
> + return;
> + entry = (struct grub_ext4_xattr_entry *)(ihdr + 1);
> + for (; (grub_uint8_t *)entry < iend && !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry))
> + {
> + grub_size_t value_size;
> + grub_off_t value_offs;
> +
> + if (entry->value_block)
> + continue;
> + if (entry->name_index != EXT4_XATTR_INDEX_SYSTEM)
> + continue;
> + if (entry->name_len != sizeof (EXT4_XATTR_SYSTEM_DATA) - 1)
> + continue;
> + if (grub_memcmp (entry->name, EXT4_XATTR_SYSTEM_DATA, sizeof (EXT4_XATTR_SYSTEM_DATA) - 1))
> + continue;
> + value_size = grub_le_to_cpu32 (entry->value_size);
> + value_offs = grub_le_to_cpu16 (entry->value_offs);
> + /* extra is additional size of base inode. Extended attributes start
> + after base inode, offset is calculated from the end of extended
> + attributes header.
> + */
> + if (EXT2_GOOD_OLD_INODE_SIZE + extra + sizeof (*ihdr) + value_offs + value_size > isize)
> + continue;
> + node->inline_offs = EXT2_GOOD_OLD_INODE_SIZE + extra + sizeof (*ihdr) + value_offs;
> + node->inline_size = value_size;
> + return;
> + }
> +}
> +
> /* Read into BLKGRP the blockgroup descriptor of blockgroup GROUP of
> the mounted filesystem DATA. */
> inline static grub_err_t
> @@ -528,6 +620,52 @@ grub_ext2_read_file (grub_fshelp_node_t node,
> grub_disk_read_hook_t read_hook, void *read_hook_data,
> grub_off_t pos, grub_size_t len, char *buf)
> {
> + /* Does inode have inine data? */
> + if (node->inline_offs)
> + {
> + grub_size_t cp_len;
> + grub_off_t cp_pos;
> + grub_ssize_t total = 0;
> +
> + if (pos < 60)
> + {
> + cp_pos = node->inode_offs + ((char *)&node->inode.blocks - (char *)&node->inode) + pos;
> + cp_len = 60 - pos;
> + if (cp_len > len)
> + cp_len = len;
> +
> + node->data->disk->read_hook = read_hook;
> + node->data->disk->read_hook_data = read_hook_data;
> + grub_disk_read (node->data->disk, node->inode_base, cp_pos,
> + cp_len, buf);
> + node->data->disk->read_hook = 0;
> + if (grub_errno)
> + return -1;
> + pos += cp_len;
> + buf += cp_len;
> + len -= cp_len;
> + total = cp_len;
> + }
> +
> + if (len)
> + {
> + pos -= 60;
> + if (pos >= node->inline_size)
> + return 0;
> + if (pos + len > node->inline_size)
> + len = node->inline_size - pos;
> + cp_pos = node->inode_offs + node->inline_offs + pos;
> + node->data->disk->read_hook = read_hook;
> + node->data->disk->read_hook_data = read_hook_data;
> + grub_disk_read (node->data->disk, node->inode_base, cp_pos,
> + len, buf);
> + node->data->disk->read_hook = 0;
> + if (!grub_errno)
> + total += len;
> + }
> + return total;
> + }
> +
> return grub_fshelp_read_file (node->data->disk, node,
> read_hook, read_hook_data,
> pos, len, buf, grub_ext2_read_block,
> @@ -538,17 +676,28 @@ grub_ext2_read_file (grub_fshelp_node_t node,
> }
>
>
> -/* Read the inode INO for the file described by DATA into INODE. */
> +/* Read the inode NODE->INO for the file described by NODE->DATA into NODE->INODE. */
> static grub_err_t
> -grub_ext2_read_inode (struct grub_ext2_data *data,
> - int ino, struct grub_ext2_inode *inode)
> +grub_ext2_read_inode (struct grub_fshelp_node *node)
> {
> + struct grub_ext2_data *data = node->data;
> + int ino = node->ino;
> struct grub_ext2_block_group blkgrp;
> struct grub_ext2_sblock *sblock = &data->sblock;
> int inodes_per_block;
> unsigned int blkno;
> unsigned int blkoff;
> grub_disk_addr_t base;
> + grub_uint8_t *full_inode;
> + grub_size_t full_isize;
> +
> + if (node->inode_read)
> + return 0;
> +
> + full_isize = EXT2_INODE_SIZE (data);
> + full_inode = grub_malloc (full_isize);
> + if (!full_inode)
> + return 0;
>
> /* It is easier to calculate if the first inode is 0. */
> ino--;
> @@ -557,9 +706,12 @@ grub_ext2_read_inode (struct grub_ext2_data *data,
> ino / grub_le_to_cpu32 (sblock->inodes_per_group),
> &blkgrp);
> if (grub_errno)
> - return grub_errno;
> + {
> + grub_free (full_inode);
> + return grub_errno;
> + }
>
> - inodes_per_block = EXT2_BLOCK_SIZE (data) / EXT2_INODE_SIZE (data);
> + inodes_per_block = EXT2_BLOCK_SIZE (data) / full_isize;
> blkno = (ino % grub_le_to_cpu32 (sblock->inodes_per_group))
> / inodes_per_block;
> blkoff = (ino % grub_le_to_cpu32 (sblock->inodes_per_group))
> @@ -571,12 +723,18 @@ grub_ext2_read_inode (struct grub_ext2_data *data,
> << 32);
>
> /* Read the inode. */
> - if (grub_disk_read (data->disk,
> - ((base + blkno) << LOG2_EXT2_BLOCK_SIZE (data)),
> - EXT2_INODE_SIZE (data) * blkoff,
> - sizeof (struct grub_ext2_inode), inode))
> - return grub_errno;
> + node->inode_base = (base + blkno) << LOG2_EXT2_BLOCK_SIZE (data);
> + node->inode_offs = full_isize * blkoff;
> + if (grub_disk_read (data->disk, node->inode_base, node->inode_offs,
> + full_isize, full_inode))
> + {
> + grub_free (full_inode);
> + return grub_errno;
> + }
> + grub_memcpy (&node->inode, full_inode, sizeof (struct grub_ext2_inode));
>
> + node->inode_read = 1;
> + grub_ext2_find_inline_data (node, full_isize, full_inode);
> return 0;
> }
>
> @@ -632,11 +790,9 @@ grub_ext2_mount (grub_disk_t disk)
>
> data->diropen.data = data;
> data->diropen.ino = 2;
> - data->diropen.inode_read = 1;
> -
> data->inode = &data->diropen.inode;
>
> - grub_ext2_read_inode (data, 2, data->inode);
> + grub_ext2_read_inode (&data->diropen);
> if (grub_errno)
> goto fail;
>
> @@ -656,12 +812,9 @@ grub_ext2_read_symlink (grub_fshelp_node_t node)
> char *symlink;
> struct grub_fshelp_node *diro = node;
>
> - if (! diro->inode_read)
> - {
> - grub_ext2_read_inode (diro->data, diro->ino, &diro->inode);
> - if (grub_errno)
> - return 0;
> - }
> + grub_ext2_read_inode (diro);
> + if (grub_errno)
> + return 0;
>
> symlink = grub_malloc (grub_le_to_cpu32 (diro->inode.size) + 1);
> if (! symlink)
> @@ -697,11 +850,42 @@ grub_ext2_iterate_dir (grub_fshelp_node_t dir,
> unsigned int fpos = 0;
> struct grub_fshelp_node *diro = (struct grub_fshelp_node *) dir;
>
> - if (! diro->inode_read)
> + grub_ext2_read_inode (diro);
> + if (grub_errno)
> + return 0;
> +
> + /* Inline directory has only parent inode number and no explicit entries
> + for . or ..; simulate them */
> + if (diro->inline_offs)
> {
> - grub_ext2_read_inode (diro->data, diro->ino, &diro->inode);
> + struct grub_fshelp_node *dot, *dotdot;
> + grub_uint32_t inum;
> +
> + dot = grub_malloc (sizeof (struct grub_fshelp_node));
> + if (!dot)
> + return 0;
> +
> + dot->inode_read = 0;
> + dot->ino = dir->ino;
> + dot->data = diro->data;
> + if (hook (".", FILETYPE_DIRECTORY, dot, hook_data))
> + return 1;
> +
> + /* First 4 bytes of inline directory data is parent inode number */
> + grub_ext2_read_file (diro, 0, 0, 0, EXT4_INLINE_DOTDOT_SIZE, (char *) &inum);
> if (grub_errno)
> return 0;
> + dotdot = grub_malloc (sizeof (struct grub_fshelp_node));
> + if (!dotdot)
> + return 0;
> +
> + dotdot->inode_read = 0;
> + dotdot->ino = grub_le_to_cpu32 (inum);
> + dotdot->data = diro->data;
> + if (hook ("..", FILETYPE_DIRECTORY, dotdot, hook_data))
> + return 1;
> +
> + fpos = EXT4_INLINE_DOTDOT_SIZE;
> }
>
> /* Search the file. */
> @@ -752,17 +936,13 @@ grub_ext2_iterate_dir (grub_fshelp_node_t dir,
> {
> /* The filetype can not be read from the dirent, read
> the inode to get more information. */
> - grub_ext2_read_inode (diro->data,
> - grub_le_to_cpu32 (dirent.inode),
> - &fdiro->inode);
> + grub_ext2_read_inode (fdiro);
> if (grub_errno)
> {
> grub_free (fdiro);
> return 0;
> }
>
> - fdiro->inode_read = 1;
> -
> if ((grub_le_to_cpu16 (fdiro->inode.mode)
> & FILETYPE_INO_MASK) == FILETYPE_INO_DIRECTORY)
> type = GRUB_FSHELP_DIR;
> @@ -807,14 +987,11 @@ grub_ext2_open (struct grub_file *file, const char *name)
> if (err)
> goto fail;
>
> - if (! fdiro->inode_read)
> - {
> - err = grub_ext2_read_inode (data, fdiro->ino, &fdiro->inode);
> - if (err)
> - goto fail;
> - }
> + err = grub_ext2_read_inode (fdiro);
> + if (err)
> + goto fail;
>
> - grub_memcpy (data->inode, &fdiro->inode, sizeof (struct grub_ext2_inode));
> + grub_memcpy (&data->diropen, fdiro, sizeof (struct grub_fshelp_node));
> grub_free (fdiro);
>
> file->size = grub_le_to_cpu32 (data->inode->size);
> @@ -873,13 +1050,9 @@ grub_ext2_dir_iter (const char *filename, enum grub_fshelp_filetype filetype,
> struct grub_dirhook_info info;
>
> grub_memset (&info, 0, sizeof (info));
> - if (! node->inode_read)
> - {
> - grub_ext2_read_inode (ctx->data, node->ino, &node->inode);
> - if (!grub_errno)
> - node->inode_read = 1;
> - grub_errno = GRUB_ERR_NONE;
> - }
> + grub_ext2_read_inode (node);
> + grub_errno = GRUB_ERR_NONE;
> +
> if (node->inode_read)
> {
> info.mtimeset = 1;
>
--
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