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Re: [PATCH 4/4] xfs: increase number of ACL entries for V5 superblocks

To: xfs@xxxxxxxxxxx
Subject: Re: [PATCH 4/4] xfs: increase number of ACL entries for V5 superblocks
From: Mark Tinguely <tinguely@xxxxxxx>
Date: Wed, 05 Jun 2013 08:38:19 -0500
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <51AF3C69.2040903@xxxxxxx>
References: <1370398150-12084-1-git-send-email-david@xxxxxxxxxxxxx> <1370398150-12084-5-git-send-email-david@xxxxxxxxxxxxx> <51AF3C69.2040903@xxxxxxx>
User-agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:9.0) Gecko/20120122 Thunderbird/9.0
On 06/05/13 08:26, Mark Tinguely wrote:
> On 06/04/13 21:09, Dave Chinner wrote:
>> From: Dave Chinner<dchinner@xxxxxxxxxx>
>>
>> The limit of 25 ACL entries is arbitrary, but baked into the on-disk
>> format. For version 5 superblocks, increase it to the maximum nuber
>> of ACLs that can fit into a single xattr.
>>
>> Signed-off-by: Dave Chinner<dchinner@xxxxxxxxxx>
>> Reviewed-by: Brian Foster<bfoster@xxxxxxxxxx>
>> ---
>
>> /* On-disk XFS access control list structure */
>> +struct xfs_acl_entry {
>> + __be32 ae_tag;
>> + __be32 ae_id;
>> + __be16 ae_perm;
>> + __be16 ae_pad; /* fill the implicit hole in the structure */
>> +};
>> +
>> struct xfs_acl {
>> - __be32 acl_cnt;
>> - struct xfs_acl_entry {
>> - __be32 ae_tag;
>> - __be32 ae_id;
>> - __be16 ae_perm;
>> - } acl_entry[XFS_ACL_MAX_ENTRIES];
>> + __be32 acl_cnt;
>> + struct xfs_acl_entry acl_entry[0];
>> };
>>
>> +/*
>> + * The number of ACL entries allowed is defined by the on-disk format.
>> + * For v4 superblocks, that is limited to 25 entries. For v5
>> superblocks, it is
>> + * limited only by the maximum size of the xattr that stores the
>> information.
>> + */
>> +#define XFS_ACL_MAX_ENTRIES(mp) \
>> + (xfs_sb_version_hascrc(&mp->m_sb) \
>> + ? (XATTR_SIZE_MAX - sizeof(struct xfs_acl)) / \
>> + sizeof(struct xfs_acl_entry) \
>> + : 25)
>> +
>> +#define XFS_ACL_MAX_SIZE(mp) \
>> + (sizeof(struct xfs_acl) + \
>> + sizeof(struct xfs_acl_entry) * XFS_ACL_MAX_ENTRIES((mp)))
>> +
>> /* On-disk XFS extended attribute names */
>> #define SGI_ACL_FILE (unsigned char *)"SGI_ACL_FILE"
>> #define SGI_ACL_DEFAULT (unsigned char *)"SGI_ACL_DEFAULT"
>
> I thought you would leave the XFS_ACL_MAX_ENTRIES(mp) as:
>

...

never mind, now I get it "struct xfs_acl_entry  acl_entry[0]" reserves
no space.

Reviewed-by: Mark Tinguely <tinuguely@xxxxxxx>


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