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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; > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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