[LU-5008] bad negative dentry caching in .lustre/fid

• Status: Open
• Project: Lustre
• Affects Version/s: Lustre 2.6.0
• Type: Bug
• Priority: Major
• Reporter: John Hammond
• Assignee: WC Triage
• Resolution: Unresolved
• Labels: fid
• Severity: 3

Description

By guessing the next FID and stating it in .lustre/fid I can cause spurious negative dentry caching. I never considered this to be a bug because we don't usually use .lustre/fid this way. But see http://review.whamcloud.com/#/c/10185/.

t:lustre# touch f0
t:lustre# lfs path2fid f0
[0x200000400:0x1:0x0]
t:lustre# sys_access .lustre/fid/[0x200000400:0x1:0x0]
t:lustre# sys_access .lustre/fid/[0x200000400:0x2:0x0]
sys_access: cannot access '.lustre/fid/[0x200000400:0x2:0x0]' with mode `f': No such file or directory
t:lustre# touch f1
t:lustre# lfs path2fid f1
[0x200000400:0x2:0x0]
t:lustre# sys_access .lustre/fid/[0x200000400:0x2:0x0]
sys_access: cannot access '.lustre/fid/[0x200000400:0x2:0x0]' with mode `f': No such file or directory
t:lustre# rm .lustre/fid/[0x200000400:0x2:0x0]
rm: cannot remove `.lustre/fid/[0x200000400:0x2:0x0]': No such file or directory
t:lustre# sys_access .lustre/fid/[0x200000400:0x2:0x0]
sys_access: cannot access '.lustre/fid/[0x200000400:0x2:0x0]' with mode `f': No such file or directory
t:lustre# rmdir .lustre/fid/
rmdir: failed to remove `.lustre/fid/': Operation not permitted
t:lustre# sys_access .lustre/fid/[0x200000400:0x2:0x0]
t:lustre# sys_stat .lustre/fid/[0x200000400:0x3:0x0]
cannot stat '.lustre/fid/[0x200000400:0x3:0x0]': No such file or directory
t:lustre# touch f2
t:lustre# lfs path2fid f2
[0x200000400:0x3:0x0]
t:lustre# sys_stat .lustre/fid/[0x200000400:0x3:0x0]
cannot stat '.lustre/fid/[0x200000400:0x3:0x0]': No such file or directory

Issue Links

• is related to: LU-11501 use the dcache properly with .lustre/fid