vfs: implement readahead(2) using POSIX_FADV_WILLNEED

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The implementation of readahead(2) syscall is identical to that of
fadvise64(POSIX_FADV_WILLNEED) with a few exceptions:
1. readahead(2) returns -EINVAL for !mapping->a_ops and fadvise64()
   ignores the request and returns 0.
2. fadvise64() checks for integer overflow corner case
3. fadvise64() calls the optional filesystem fadvise() file operation

Unite the two implementations by calling vfs_fadvise() from readahead(2)
syscall. Check the !mapping->a_ops in readahead(2) syscall to preserve
documented syscall ABI behaviour.

Suggested-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: d1d04ef857 ("ovl: stack file ops")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

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Amir Goldstein 2018-08-29 08:41:29 +03:00 • committed by Miklos Szeredi

parent 45cd0faae3

commit 3d8f761531

3 changed files with 21 additions and 30 deletions

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3

mm/Makefile

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3

mm/fadvise.c

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45

mm/readahead.c

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