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author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2021-05-05 03:32:45 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-05-05 20:27:19 +0200 |
commit | 7716506adac4664793a9d6d3dfa31ffddfa98714 (patch) | |
tree | ec099a414e8120e3e68e2e6022eed8fa6fff5a3b | |
parent | mm/memory-failure: unnecessary amount of unmapping (diff) | |
download | linux-7716506adac4664793a9d6d3dfa31ffddfa98714.tar.xz linux-7716506adac4664793a9d6d3dfa31ffddfa98714.zip |
mm: introduce and use mapping_empty()
Patch series "Remove nrexceptional tracking", v2.
We actually use nrexceptional for very little these days. It's a minor
pain to keep in sync with nrpages, but the pain becomes much bigger with
the THP patches because we don't know how many indices a shadow entry
occupies. It's easier to just remove it than keep it accurate.
Also, we save 8 bytes per inode which is nothing to sneeze at; on my
laptop, it would improve shmem_inode_cache from 22 to 23 objects per
16kB, and inode_cache from 26 to 27 objects. Combined, that saves
a megabyte of memory from a combined usage of 25MB for both caches.
Unfortunately, ext4 doesn't cross a magic boundary, so it doesn't save
any memory for ext4.
This patch (of 4):
Instead of checking the two counters (nrpages and nrexceptional), we can
just check whether i_pages is empty.
Link: https://lkml.kernel.org/r/20201026151849.24232-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20201026151849.24232-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: Vishal Verma <vishal.l.verma@intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | fs/block_dev.c | 2 | ||||
-rw-r--r-- | fs/dax.c | 2 | ||||
-rw-r--r-- | fs/gfs2/glock.c | 3 | ||||
-rw-r--r-- | include/linux/pagemap.h | 5 | ||||
-rw-r--r-- | mm/truncate.c | 18 |
5 files changed, 11 insertions, 19 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index a5244e08b6c8..9114e0a0e7b4 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -79,7 +79,7 @@ static void kill_bdev(struct block_device *bdev) { struct address_space *mapping = bdev->bd_inode->i_mapping; - if (mapping->nrpages == 0 && mapping->nrexceptional == 0) + if (mapping_empty(mapping)) return; invalidate_bh_lrus(); @@ -965,7 +965,7 @@ int dax_writeback_mapping_range(struct address_space *mapping, if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT)) return -EIO; - if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL) + if (mapping_empty(mapping) || wbc->sync_mode != WB_SYNC_ALL) return 0; trace_dax_writeback_range(inode, xas.xa_index, end_index); diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 84c38103aa06..ea7fc5c641c7 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -273,8 +273,7 @@ static void __gfs2_glock_put(struct gfs2_glock *gl) if (mapping) { truncate_inode_pages_final(mapping); if (!gfs2_withdrawn(sdp)) - GLOCK_BUG_ON(gl, mapping->nrpages || - mapping->nrexceptional); + GLOCK_BUG_ON(gl, !mapping_empty(mapping)); } trace_gfs2_glock_put(gl); sdp->sd_lockstruct.ls_ops->lm_put_lock(gl); diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 469fa7ffcf96..a4bd41128bf3 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -18,6 +18,11 @@ struct pagevec; +static inline bool mapping_empty(struct address_space *mapping) +{ + return xa_empty(&mapping->i_pages); +} + /* * Bits in mapping->flags. */ diff --git a/mm/truncate.c b/mm/truncate.c index 455944264663..adb8d4107988 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -295,7 +295,7 @@ void truncate_inode_pages_range(struct address_space *mapping, pgoff_t index; int i; - if (mapping->nrpages == 0 && mapping->nrexceptional == 0) + if (mapping_empty(mapping)) goto out; /* Offsets within partial pages */ @@ -440,9 +440,6 @@ EXPORT_SYMBOL(truncate_inode_pages); */ void truncate_inode_pages_final(struct address_space *mapping) { - unsigned long nrexceptional; - unsigned long nrpages; - /* * Page reclaim can not participate in regular inode lifetime * management (can't call iput()) and thus can race with the @@ -452,16 +449,7 @@ void truncate_inode_pages_final(struct address_space *mapping) */ mapping_set_exiting(mapping); - /* - * When reclaim installs eviction entries, it increases - * nrexceptional first, then decreases nrpages. Make sure we see - * this in the right order or we might miss an entry. - */ - nrpages = mapping->nrpages; - smp_rmb(); - nrexceptional = mapping->nrexceptional; - - if (nrpages || nrexceptional) { + if (!mapping_empty(mapping)) { /* * As truncation uses a lockless tree lookup, cycle * the tree lock to make sure any ongoing tree @@ -633,7 +621,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping, int ret2 = 0; int did_range_unmap = 0; - if (mapping->nrpages == 0 && mapping->nrexceptional == 0) + if (mapping_empty(mapping)) goto out; pagevec_init(&pvec); |