vfs: change sb->s_maxbytes to a loff_t
sb->s_maxbytes is supposed to indicate the maximum size of a file that can exist on the filesystem. It's declared as an unsigned long long. Even if a filesystem has no inherent limit that prevents it from using every bit in that unsigned long long, it's still problematic to set it to anything larger than MAX_LFS_FILESIZE. There are places in the kernel that cast s_maxbytes to a signed value. If it's set too large then this cast makes it a negative number and generally breaks the comparison. Change s_maxbytes to be loff_t instead. That should help eliminate the temptation to set it too large by making it a signed value. Also, add a warning for couple of releases to help catch filesystems that set s_maxbytes too large. Eventually we can either convert this to a BUG() or just remove it and in the hope that no one will get it wrong now that it's a signed value. Signed-off-by: Jeff Layton <jlayton@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Robert Love <rlove@google.com> Cc: Mandeep Singh Baines <msb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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5aa98b706e
Коммит
42cb56ae2a
10
fs/super.c
10
fs/super.c
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@ -892,6 +892,16 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
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if (error)
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goto out_sb;
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/*
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* filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
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* but s_maxbytes was an unsigned long long for many releases. Throw
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* this warning for a little while to try and catch filesystems that
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* violate this rule. This warning should be either removed or
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* converted to a BUG() in 2.6.34.
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*/
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WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
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"negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes);
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mnt->mnt_mountpoint = mnt->mnt_root;
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mnt->mnt_parent = mnt;
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up_write(&mnt->mnt_sb->s_umount);
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@ -1315,7 +1315,7 @@ struct super_block {
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unsigned long s_blocksize;
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unsigned char s_blocksize_bits;
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unsigned char s_dirt;
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unsigned long long s_maxbytes; /* Max file size */
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loff_t s_maxbytes; /* Max file size */
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struct file_system_type *s_type;
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const struct super_operations *s_op;
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const struct dquot_operations *dq_op;
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