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quota: add get_inode_usage callback to transfer multi-inode charges

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Ext4 ea_inode feature allows storing xattr values in external inodes to
be able to store values that are bigger than a block in size. Ext4 also
has deduplication support for these type of inodes. With deduplication,
the actual storage waste is eliminated but the users of such inodes are
still charged full quota for the inodes as if there was no sharing
happening in the background.

This design requires ext4 to manually charge the users because the
inodes are shared.

An implication of this is that, if someone calls chown on a file that
has such references we need to transfer the quota for the file and xattr
inodes. Current dquot_transfer() function implicitly transfers one inode
charge. With ea_inode feature, we would like to transfer multiple inode
charges.

Add get_inode_usage callback which can interrogate the total number of
inodes that were charged for a given inode.

[ Applied fix from Colin King to make sure the 'ret' variable is
  initialized on the successful return path.  Detected by
  CoverityScan, CID#1446616 ("Uninitialized scalar variable") --tytso]

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Tahsin Erdogan
2017-06-22 11:46:48 -04:00
committed by Theodore Ts'o
parent dec214d00e
commit 7a9ca53aea
7 changed files with 95 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
fs/ext4/inode.c
View File

@@ -5295,7 +5295,14 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
error = PTR_ERR(handle);
goto err_out;
}
/* dquot_transfer() calls back ext4_get_inode_usage() which
* counts xattr inode references.
*/
down_read(&EXT4_I(inode)->xattr_sem);
error = dquot_transfer(inode, attr);
up_read(&EXT4_I(inode)->xattr_sem);
if (error) {
ext4_journal_stop(handle);
return error;

6
fs/ext4/ioctl.c
View File

@@ -373,7 +373,13 @@ static int ext4_ioctl_setproject(struct file *filp, __u32 projid)
transfer_to[PRJQUOTA] = dqget(sb, make_kqid_projid(kprojid));
if (!IS_ERR(transfer_to[PRJQUOTA])) {
/* __dquot_transfer() calls back ext4_get_inode_usage() which
* counts xattr inode references.
*/
down_read(&EXT4_I(inode)->xattr_sem);
err = __dquot_transfer(inode, transfer_to);
up_read(&EXT4_I(inode)->xattr_sem);
dqput(transfer_to[PRJQUOTA]);
if (err)
goto out_dirty;

21
fs/ext4/super.c
View File

@@ -1263,16 +1263,17 @@ static struct dquot **ext4_get_dquots(struct inode *inode)
}
static const struct dquot_operations ext4_quota_operations = {
.get_reserved_space = ext4_get_reserved_space,
.write_dquot = ext4_write_dquot,
.acquire_dquot = ext4_acquire_dquot,
.release_dquot = ext4_release_dquot,
.mark_dirty = ext4_mark_dquot_dirty,
.write_info = ext4_write_info,
.alloc_dquot = dquot_alloc,
.destroy_dquot = dquot_destroy,
.get_projid = ext4_get_projid,
.get_next_id = ext4_get_next_id,
.get_reserved_space = ext4_get_reserved_space,
.write_dquot = ext4_write_dquot,
.acquire_dquot = ext4_acquire_dquot,
.release_dquot = ext4_release_dquot,
.mark_dirty = ext4_mark_dquot_dirty,
.write_info = ext4_write_info,
.alloc_dquot = dquot_alloc,
.destroy_dquot = dquot_destroy,
.get_projid = ext4_get_projid,
.get_inode_usage = ext4_get_inode_usage,
.get_next_id = ext4_get_next_id,
};
static const struct quotactl_ops ext4_qctl_operations = {

55
fs/ext4/xattr.c
View File

@@ -733,6 +733,61 @@ static void ext4_xattr_update_super_block(handle_t *handle,
}
}
int ext4_get_inode_usage(struct inode *inode, qsize_t *usage)
{
struct ext4_iloc iloc = { .bh = NULL };
struct buffer_head *bh = NULL;
struct ext4_inode *raw_inode;
struct ext4_xattr_ibody_header *header;
struct ext4_xattr_entry *entry;
qsize_t ea_inode_refs = 0;
void *end;
int ret;
lockdep_assert_held_read(&EXT4_I(inode)->xattr_sem);
if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
ret = ext4_get_inode_loc(inode, &iloc);
if (ret)
goto out;
raw_inode = ext4_raw_inode(&iloc);
header = IHDR(inode, raw_inode);
end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
ret = xattr_check_inode(inode, header, end);
if (ret)
goto out;
for (entry = IFIRST(header); !IS_LAST_ENTRY(entry);
entry = EXT4_XATTR_NEXT(entry))
if (entry->e_value_inum)
ea_inode_refs++;
}
if (EXT4_I(inode)->i_file_acl) {
bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
if (!bh) {
ret = -EIO;
goto out;
}
if (ext4_xattr_check_block(inode, bh)) {
ret = -EFSCORRUPTED;
goto out;
}
for (entry = BFIRST(bh); !IS_LAST_ENTRY(entry);
entry = EXT4_XATTR_NEXT(entry))
if (entry->e_value_inum)
ea_inode_refs++;
}
*usage = ea_inode_refs + 1;
ret = 0;
out:
brelse(iloc.bh);
brelse(bh);
return ret;
}
static inline size_t round_up_cluster(struct inode *inode, size_t length)
{
struct super_block *sb = inode->i_sb;

2
fs/ext4/xattr.h
View File

@@ -193,3 +193,5 @@ extern void ext4_xattr_inode_set_class(struct inode *ea_inode);
#else
static inline void ext4_xattr_inode_set_class(struct inode *ea_inode) { }
#endif
extern int ext4_get_inode_usage(struct inode *inode, qsize_t *usage);