1IOCTL-XFS-GETRESBLKS(2)       System Calls Manual      IOCTL-XFS-GETRESBLKS(2)
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NAME

6       ioctl_xfs_getresblks  - query and set XFS free space reservation infor‐
7       mation
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SYNOPSIS

10       #include <xfs/xfs_fs.h>
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12       int ioctl(int fd, XFS_IOC_GET_RESBLKS, struct xfs_fsop_resblks *arg);
13       int ioctl(int fd, XFS_IOC_SET_RESBLKS, struct xfs_fsop_resblks *arg);
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DESCRIPTION

16       Query or set the free space reservation information.  These blocks  are
17       reserved  by  the  filesystem  as  a  final attempt to prevent metadata
18       update failures due to insufficient space.  Only the system administra‐
19       tor  can use these ioctls, because overriding the defaults is extremely
20       dangerous.
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22       This functionality is intended only for use by XFS filesystem  develop‐
23       ers.
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25       The reservation information is conveyed in a structure of the following
26       form:
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28           struct xfs_fsop_resblks {
29                __u64  resblks;
30                __u64  resblks_avail;
31           };
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33       resblks is the number of blocks that the filesystem will try  to  main‐
34       tain to prevent critical out of space situations.
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36       resblks_avail is the number of reserved blocks remaining.
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RETURN VALUE

39       On error, -1 is returned, and errno is set to indicate the error.
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ERRORS

42       Error codes can be one of, but are not limited to, the following:
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44       EFSBADCRC
45              Metadata checksum validation failed while performing the query.
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47       EFSCORRUPTED
48              Metadata corruption was encountered while performing the query.
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50       EINVAL The  specified  allocation  group  number  is not valid for this
51              filesystem.
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53       EIO    An I/O error was encountered while performing the query.
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55       EPERM  Caller does not have permission to call this ioctl.
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CONFORMING TO

58       This API is specific to XFS filesystem on the Linux kernel.
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SEE ALSO

61       ioctl(2)
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65XFS                               2019-06-17           IOCTL-XFS-GETRESBLKS(2)
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