- 26 12月, 2017 1 次提交
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由 NeilBrown 提交于
The original purpose of the per-superblock d_anon list was to keep disconnected dentries in the cache between consecutive requests to the NFS server. Dentries can be disconnected if a client holds a file open and repeatedly performs IO on it, and if the server drops the dentry, whether due to memory pressure, server restart, or "echo 3 > /proc/sys/vm/drop_caches". This purpose was thwarted by commit 75a6f82a ("freeing unlinked file indefinitely delayed") which caused disconnected dentries to be freed as soon as their refcount reached zero. This means that, when a dentry being used by nfsd gets disconnected, a new one needs to be allocated for every request (unless requests overlap). As the dentry has no name, no parent, and no children, there is little of value to cache. As small memory allocations are typically fast (from per-cpu free lists) this likely has little cost. This means that the original purpose of s_anon is no longer relevant: there is no longer any need to keep disconnected dentries on a list so they appear to be hashed. However, s_anon now has a new use. When you mount an NFS filesystem, the dentry stored in s_root is just a placebo. The "real" root dentry is allocated using d_obtain_root() and so it kept on the s_anon list. I don't know the reason for this, but suspect it related to NFSv4 where a mount of "server:/some/path" require NFS to look up the root filehandle on the server, then walk down "/some" and "/path" to get the filehandle to mount. Whatever the reason, NFS depends on the s_anon list and on shrink_dcache_for_umount() pruning all dentries on this list. So we cannot simply remove s_anon. We could just leave the code unchanged, but apart from that being potentially confusing, the (unfair) bit-spin-lock which protects s_anon can become a bottle neck when lots of disconnected dentries are being created. So this patch renames s_anon to s_roots, and stops storing disconnected dentries on the list. Only dentries obtained with d_obtain_root() are now stored on this list. There are many fewer of these (only NFS and NILFS2 use the call, and only during filesystem mount) so contention on the bit-lock will not be a problem. Possibly an alternate solution should be found for NFS and NILFS2, but that would require understanding their needs first. Signed-off-by: NNeilBrown <neilb@suse.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 20 11月, 2014 1 次提交
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 08 8月, 2014 1 次提交
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由 J. Bruce Fields 提交于
Minor documentation updates: - refer to d_obtain_alias rather than d_alloc_anon - explain when to use d_splice_alias and when d_materialise_unique. - cut some details of d_splice_alias/d_materialise_unique implementation. Signed-off-by: NJ. Bruce Fields <bfields@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 20 8月, 2013 1 次提交
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由 Masanari Iida 提交于
Correct spelling typo in Documentations/filesystems. Signed-off-by: NMasanari Iida <standby24x7@gmail.com> Acked-by: NRandy Dunlap <rdunlap@infradead.org> Signed-off-by: NJiri Kosina <jkosina@suse.cz>
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- 27 7月, 2011 1 次提交
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由 Phillip Lougher 提交于
Following commits a9049376 and 0c1aa9a9 update the d_splice_alias desciption. Signed-off-by: NPhillip Lougher <phillip@squashfs.org.uk> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 28 10月, 2009 1 次提交
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由 J. Bruce Fields 提交于
We're adding enough nfs documentation that it may as well have its own subdirectory. Acked-by: NRandy Dunlap <rdunlap@xenotime.net> Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
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- 22 10月, 2007 1 次提交
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由 Christoph Hellwig 提交于
Update documentation to the current state of affairs. Remove duplicated method descruptions in exportfs.h and point to Documentation/filesystems/ Exporting instead. Add a little file header comment in expfs.c describing what's going on and mentioning Neils and my copyright [1]. Signed-off-by: NChristoph Hellwig <hch@lst.de> Cc: Neil Brown <neilb@suse.de> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: <linux-ext4@vger.kernel.org> Cc: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: David Chinner <dgc@sgi.com> Cc: Timothy Shimmin <tes@sgi.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Hugh Dickins <hugh@veritas.com> Cc: Chris Mason <mason@suse.com> Cc: Jeff Mahoney <jeffm@suse.com> Cc: "Vladimir V. Saveliev" <vs@namesys.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 17 4月, 2005 1 次提交
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由 Linus Torvalds 提交于
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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