1IOCTL-XFS-GETBMAPX(2) System Calls Manual IOCTL-XFS-GETBMAPX(2)
2
6 ioctl_xfs_getbmapx - query extent information for an open file
7
9 #include <xfs/xfs_fs.h>
10 int ioctl(int fd, XFS_IOC_GETBMAP, struct getbmap *arg);
12 int ioctl(int fd, XFS_IOC_GETBMAPA, struct getbmap *arg);
13 int ioctl(int fd, XFS_IOC_GETBMAPX, struct getbmapx *arg);
14
16 Get the block map for a segment of a file in an XFS file system. The
17 mapping information is conveyed via an array of structures of the fol‐
18 lowing form:
19 struct getbmap {
21 __s64 bmv_offset;
22 __s64 bmv_block;
23 __s64 bmv_length;
24 __s32 bmv_count;
25 __s32 bmv_entries;
26 };
27 The XFS_IOC_GETBMAPX ioctl uses a larger version of that structure:
29 struct getbmapx {
31 __s64 bmv_offset;
32 __s64 bmv_block;
33 __s64 bmv_length;
34 __s32 bmv_count;
35 __s32 bmv_entries;
36 __s32 bmv_iflags;
37 __s32 bmv_oflags;
38 __s32 bmv_unused1;
39 __s32 bmv_unused2;
40 };
41 All sizes and offsets in the structure are in units of 512 bytes.
43 The first structure in the array is a header and the remaining struc‐
45 tures in the array contain block map information on return. The header
46 controls iterative calls to the command and should be filled out as
47 follows:
48 bmv_offset
50 The file offset of the area of interest in the file.
51 bmv_length
53 The length of the area of interest in the file. If this value
54 is set to -1, the length of the interesting area is the rest of
55 the file.
56 bmv_count
58 The number of elements in the array, including this header. The
59 minimum value is 2.
60 bmv_entries
62 The number of entries actually filled in by the call. This does
63 not need to be filled out before the call. This value may be
64 zero if no extents were found in the requested range, or if
65 iterated calls have reached the end of the requested range.
66 bmv_iflags
68 For the XFS_IOC_GETBMAPX function, this is a bitmask containing
69 a combination of the following flags:
70 BMV_IF_ATTRFORK
72 Return information about the extended attribute fork.
73 BMV_IF_PREALLOC
75 Return information about unwritten pre-allocated segments.
76 BMV_IF_DELALLOC
78 Return information about delayed allocation reservation seg‐
79 ments.
80 BMV_IF_NO_HOLES
82 Do not return information about holes.
83 The other bmv_* fields in the header are ignored.
85 On successful return from a call, the offset and length values in the
87 header are updated so that the command can be reused to obtain more
88 information. The remaining elements of the array will be filled out by
89 the call as follows:
90 bmv_offset
92 File offset of segment.
93 bmv_block
95 Physical starting block of segment. If this is -1, then the
96 segment is a hole.
97 bmv_length
99 Length of segment.
100 bmv_oflags
102 The XFS_IOC_GETBMAPX function will fill this field with a combi‐
103 nation of the following flags:
104 BMV_OF_PREALLOC
106 The segment is an unwritten pre-allocation.
107 BMV_OF_DELALLOC
109 The segment is a delayed allocation reservation.
110 BMV_OF_LAST
112 This segment is the last in the file.
113 BMV_OF_SHARED
115 This segment shares blocks with other files.
116 The other bmv_* fields are unused in the array of output records.
118 The XFS_IOC_GETBMAPA command is identical to XFS_IOC_GETBMAP except
120 that information about the attribute fork of the file is returned.
121
123 On error, -1 is returned, and errno is set to indicate the error.
124
126 Error codes can be one of, but are not limited to, the following:
127 EFAULT The kernel was not able to copy into the userspace buffer.
129 EFSBADCRC
131 Metadata checksum validation failed while performing the query.
132 EFSCORRUPTED
134 Metadata corruption was encountered while performing the query.
135 EINVAL One of the arguments was not valid.
137 EIO An I/O error was encountered while performing the query.
139 ENOMEM There was insufficient memory to perform the query.
141
143 This API is specific to XFS filesystem on the Linux kernel.
144
146 ioctl(2)
147XFS 2019-06-17 IOCTL-XFS-GETBMAPX(2)