Checklist/Inotify

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(Created page with '== Issues and potential solutions with checkpoint/restart of inotify state == 1. Wait descriptors refer to inodes but mentioning inode numbers in checkpoint images is forbidden…')
 
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== Issues and potential solutions with checkpoint/restart of inotify state ==
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== Current Status ==
  
1. Wait descriptors refer to inodes but mentioning inode numbers in checkpoint images is forbidden.
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Any task using inotify will cause sys_checkpoint() to return failure because the file its fd refers to lacks the .checkpoint file operation. See [[UncheckpointableFilesystems]].
  1. Use dentry aliases to find a path to store in the checkpoint image
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  2. Change policy re: inode numbers in checkpoint images
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== Issues, Solutions, Impacts ==
    * Add a flag passed from userspace indicating whether inodes should be allowed in the checkpoint image.
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    * Fail or fallback to dentry alias solution if the flag is missing
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=== Summary ===
    * Return some indication of whether there are inode numbers in the checkpoint?
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      * This affects the method used to checkpoint the filesystems.
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{| border="1"
  3. Ignore inotify, which would likely be ugly, and "do it right" with fanotify instead. (Al might like this idea)
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! Issue !! Solution(s) !! Current Impact !! Solution Impact
2. Races between filesystem checkpoint and event queue checkpoint.
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|-
  * No solutions yet. fanotify may have this issue too.
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! Wait descriptors
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| Yes || None || Ugly (nothing new as far as inotify is concerned -- see existing comments in the code)
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|-
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! Event queue races
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| Unknown || None || Probably ugly
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|-
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|}
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=== Details ===
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# Wait descriptors refer to inodes but mentioning inode numbers in checkpoint images is forbidden.
 +
## Use dentry aliases to find a path to store in the checkpoint image
 +
## Change policy re: inode numbers in checkpoint images
 +
##* Add a flag passed from userspace indicating whether inodes should be allowed in the checkpoint image.
 +
##* Fail or fallback to dentry alias solution if the flag is missing
 +
##* Return some indication of whether there are inode numbers in the checkpoint?
 +
##** This affects the method used to checkpoint the filesystems.
 +
# Races between filesystem checkpoint and event queue checkpoint.
 +
#* No solutions yet. fanotify may have this issue too.

Latest revision as of 04:01, 22 February 2010

Contents

[edit] Current Status

Any task using inotify will cause sys_checkpoint() to return failure because the file its fd refers to lacks the .checkpoint file operation. See UncheckpointableFilesystems.

[edit] Issues, Solutions, Impacts

[edit] Summary

Issue Solution(s) Current Impact Solution Impact
Wait descriptors Yes None Ugly (nothing new as far as inotify is concerned -- see existing comments in the code)
Event queue races Unknown None Probably ugly

[edit] Details

  1. Wait descriptors refer to inodes but mentioning inode numbers in checkpoint images is forbidden.
    1. Use dentry aliases to find a path to store in the checkpoint image
    2. Change policy re: inode numbers in checkpoint images
      • Add a flag passed from userspace indicating whether inodes should be allowed in the checkpoint image.
      • Fail or fallback to dentry alias solution if the flag is missing
      • Return some indication of whether there are inode numbers in the checkpoint?
        • This affects the method used to checkpoint the filesystems.
  2. Races between filesystem checkpoint and event queue checkpoint.
    • No solutions yet. fanotify may have this issue too.
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