[LU-5746] llapi: fid2path doesn't return all the names associated with a fid

• Type: Bug
• Resolution: Not a Bug
• Priority: Minor
• Severity: 3
• Assignee: Andreas Dilger
• Reporter: Frank Zago (Inactive)

Description

llapi_fid2path can (or should) enumerate all the files associated with a fid, by using the linkno parameter. This is supported by lfs.

However when the number of hard link is big, this is no longer true. For instance, create a file, and many hardlinks to it:

cd /mnt/lustre/test/
touch foo
count=1; while [[ $count -le 180 ]]; do ln foo alinktofoo$count; (( count++ )) ; done

Get the fid of the file

# ~/lustre-cleanup/lustre/utils/lfs path2fid ./foo
[0x200000400:0x8b8:0x0]

and then call fid2path on it:

# ~/lustre-cleanup/lustre/utils/lfs fid2path /mnt/lustre/ 0x200000400:0x8b8:0x0

The output will be something like

/mnt/lustre/test/foo
/mnt/lustre/test/alinktofoo1
/mnt/lustre/test/alinktofoo2
/mnt/lustre/test/alinktofoo3
/mnt/lustre/test/alinktofoo4
.......
/mnt/lustre/test/alinktofoo130
/mnt/lustre/test/alinktofoo131
/mnt/lustre/test/alinktofoo132

Only the first 133 entries are returned, leaving out 47.

The interesting thing is that if the names of the links are longer (replace alinktofoo$count with averylinktofoo$count), then even less names will be returned.

Potential impact on existing programs is unknown.