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ext4: support simple conversion of extent-mapped inodes to use i_blocks 

In order to make it simpler to test the code which support
i_blocks/indirect-mapped inodes, support the conversion of inodes
which are less than 12 blocks and which are contained in no more than
a single extent.

The primary intended use of this code is to converting freshly created
zero-length files and empty directories.

Note that the version of chattr in e2fsprogs 1.42.7 and earlier has a
check that prevents the clearing of the extent flag.  A simple patch
which allows "chattr -e <file>" to work will be checked into the
e2fsprogs git repository.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2013-04-03 22:04:52 -04:00
parent d76a3a7711
commit 996bb9fddd
3 changed files with 69 additions and 13 deletions
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3
fs/ext4/ext4.h
View File

@ -403,7 +403,7 @@ struct flex_groups {
#define EXT4_RESERVED_FL 0x80000000 /* reserved for ext4 lib */
#define EXT4_FL_USER_VISIBLE 0x004BDFFF /* User visible flags */
#define EXT4_FL_USER_MODIFIABLE 0x004B80FF /* User modifiable flags */
#define EXT4_FL_USER_MODIFIABLE 0x004380FF /* User modifiable flags */
/* Flags that should be inherited by new inodes from their parent. */
#define EXT4_FL_INHERITED (EXT4_SECRM_FL | EXT4_UNRM_FL | EXT4_COMPR_FL |\
@ -2608,6 +2608,7 @@ extern int ext4_find_delalloc_range(struct inode *inode,
extern int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk);
extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
__u64 start, __u64 len);
extern int ext4_ind_migrate(struct inode *inode);
/* move_extent.c */

59
fs/ext4/extents.c
View File

@ -4610,3 +4610,62 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
return error;
}
/*
* Migrate a simple extent-based inode to use the i_blocks[] array
*/
int ext4_ind_migrate(struct inode *inode)
{
struct ext4_extent_header *eh;
struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
struct ext4_inode_info *ei = EXT4_I(inode);
struct ext4_extent *ex;
unsigned int i, len;
ext4_fsblk_t blk;
handle_t *handle;
int ret;
if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
EXT4_FEATURE_INCOMPAT_EXTENTS) ||
(!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
return -EINVAL;
down_write(&EXT4_I(inode)->i_data_sem);
ret = ext4_ext_check_inode(inode);
if (ret)
goto errout;
eh = ext_inode_hdr(inode);
ex = EXT_FIRST_EXTENT(eh);
if (ext4_blocks_count(es) > EXT4_MAX_BLOCK_FILE_PHYS ||
eh->eh_depth != 0 || eh->eh_entries > 1) {
ret = -EOPNOTSUPP;
goto errout;
}
if (eh->eh_entries == 0)
blk = len = 0;
else {
len = le16_to_cpu(ex->ee_len);
blk = ext4_ext_pblock(ex);
if (len > EXT4_NDIR_BLOCKS) {
ret = -EOPNOTSUPP;
goto errout;
}
}
handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
goto errout;
}
ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
memset(ei->i_data, 0, sizeof(ei->i_data));
for (i=0; i < len; i++)
ei->i_data[i] = cpu_to_le32(blk++);
ext4_mark_inode_dirty(handle, inode);
ext4_journal_stop(handle);
errout:
up_write(&EXT4_I(inode)->i_data_sem);
return ret;
}

20
fs/ext4/ioctl.c
View File

@ -83,17 +83,8 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
if (!capable(CAP_SYS_RESOURCE))
goto flags_out;
}
if (oldflags & EXT4_EXTENTS_FL) {
/* We don't support clearning extent flags */
if (!(flags & EXT4_EXTENTS_FL)) {
err = -EOPNOTSUPP;
goto flags_out;
}
} else if (flags & EXT4_EXTENTS_FL) {
/* migrate the file */
if ((flags ^ oldflags) & EXT4_EXTENTS_FL)
migrate = 1;
flags &= ~EXT4_EXTENTS_FL;
}
if (flags & EXT4_EOFBLOCKS_FL) {
/* we don't support adding EOFBLOCKS flag */
@ -137,8 +128,13 @@ flags_err:
err = ext4_change_inode_journal_flag(inode, jflag);
if (err)
goto flags_out;
if (migrate)
err = ext4_ext_migrate(inode);
if (migrate) {
if (flags & EXT4_EXTENTS_FL)
err = ext4_ext_migrate(inode);
else
err = ext4_ind_migrate(inode);
}
flags_out:
mutex_unlock(&inode->i_mutex);
mnt_drop_write_file(filp);