[LU-16480] Lustre fiemap does not properly handle fm_extent_count=0

• Type: Bug
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.16.0, Lustre 2.15.5
• Labels: patch
• Severity: 3
• Assignee: Andrew Perepechko
• Reporter: Andrew Perepechko

Description

"fm_extent_count specifies the number of elements in the fm_extents[] array that can be used to return extents. If fm_extent_count is zero, then the fm_extents[] array is ignored (no extents will be returned), and the fm_mapped_extents count will hold the number of extents needed in fm_extents[] to hold the file’s current mapping."

 

https://www.kernel.org/doc/html/latest/filesystems/fiemap.html

 

In practice, depending on the state of the kernel thread stack, EINVAL can be returned to userspace even for simple single stripe files.

 

Details will follow.

Issue Links

• is related to: LU-17110 Slab corruption using fiemap ioctl with fm_extent_count==0

Comments

[Gerrit Updater]

"Oleg Drokin <[e-mail]>" merged in patch https://review.whamcloud.com/c/fs/lustre-release/+/52308/
Subject: LU-16480 lov: fiemap improperly handles fm_extent_count=0
Project: fs/lustre-release
Branch: b2_15
Current Patch Set:
Commit: f8b92476350115e85efe77be8711d25b6a0ec9f7

[Gerrit Updater]

"Etienne AUJAMES <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/52308
Subject: LU-16480 lov: fiemap improperly handles fm_extent_count=0
Project: fs/lustre-release
Branch: b2_15
Current Patch Set: 1
Commit: 761fe3e18a625d0abf6168a1f6f3d3ce6a10af2b

[Peter Jones]

Landed for 2.16

[Gerrit Updater]

"Oleg Drokin <[e-mail]>" merged in patch https://review.whamcloud.com/c/fs/lustre-release/+/49645/
Subject: LU-16480 lov: fiemap improperly handles fm_extent_count=0
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 829af7b029d8e4e391b93792bf5214611b0193bd

[Gerrit Updater]

"Andrew Perepechko <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/49645
Subject: LU-16480 lov: fiemap improperly handles fm_extent_count=0
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: b787e4d0cf40569121980d2a984e0ae7f1b255b0