8 files changed, 63 insertions, 31 deletions
diff --git a/MediaBrowser.Controller/Entities/Audio/MusicArtist.cs b/MediaBrowser.Controller/Entities/Audio/MusicArtist.cs
index c25694aba5..1e2d94d2a4 100644
--- a/MediaBrowser.Controller/Entities/Audio/MusicArtist.cs
+++ b/MediaBrowser.Controller/Entities/Audio/MusicArtist.cs
@@ -173,10 +173,7 @@ namespace MediaBrowser.Controller.Entities.Audio
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validName = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validName = normalizeName ? GetItemByNameFolderName(name) : name;
 
             return System.IO.Path.Combine(ConfigurationManager.ApplicationPaths.ArtistsPath, validName);
         }
diff --git a/MediaBrowser.Controller/Entities/Audio/MusicGenre.cs b/MediaBrowser.Controller/Entities/Audio/MusicGenre.cs
index 65669e6804..23b3341dbc 100644
--- a/MediaBrowser.Controller/Entities/Audio/MusicGenre.cs
+++ b/MediaBrowser.Controller/Entities/Audio/MusicGenre.cs
@@ -80,10 +80,7 @@ namespace MediaBrowser.Controller.Entities.Audio
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validName = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validName = normalizeName ? GetItemByNameFolderName(name) : name;
 
             return System.IO.Path.Combine(ConfigurationManager.ApplicationPaths.MusicGenrePath, validName);
         }
diff --git a/MediaBrowser.Controller/Entities/BaseItem.cs b/MediaBrowser.Controller/Entities/BaseItem.cs
index 28f40cb7fa..d030c8f420 100644
--- a/MediaBrowser.Controller/Entities/BaseItem.cs
+++ b/MediaBrowser.Controller/Entities/BaseItem.cs
@@ -48,6 +48,10 @@ namespace MediaBrowser.Controller.Entities
 
         public const string ThemeSongFileName = "theme";
 
+        // Well below the 255 byte limit of the common Linux filesystems and the 255 character limit
+        // of Windows, so the files inside the folder still fit within MAX_PATH.
+        private const int MaxItemByNameFolderNameBytes = 128;
+
         /// <summary>
         /// The supported image extensions.
         /// </summary>
@@ -942,6 +946,43 @@ namespace MediaBrowser.Controller.Entities
         }
 
         /// <summary>
+        /// Turns an item-by-name entity's name into a folder name every supported filesystem accepts.
+        /// </summary>
+        /// <param name="name">The entity's name.</param>
+        /// <returns>The folder name.</returns>
+        public static string GetItemByNameFolderName(string name)
+        {
+            // Trim the period at the end because windows will have a hard time with that
+            var validName = FileSystem.GetValidFilename(name).Trim().TrimEnd('.');
+
+            // Most Linux filesystems cap a path component at 255 bytes, so a name past that cannot be
+            // turned into a folder at all - and an entity with no folder can never be created, which
+            // leaves the credit behind it stuck: not refreshable, not deletable, retried on every scan.
+            // Only broken provider data gets this long, but it still has to resolve to something, so
+            // keep a readable prefix and let a hash of the whole name tell two of them apart.
+            if (Encoding.UTF8.GetByteCount(validName) <= MaxItemByNameFolderNameBytes)
+            {
+                return validName;
+            }
+
+            var suffix = "-" + validName.GetMD5().ToString("N", CultureInfo.InvariantCulture);
+            var budget = MaxItemByNameFolderNameBytes - suffix.Length;
+            var length = Math.Min(validName.Length, budget);
+            while (length > 0 && Encoding.UTF8.GetByteCount(validName.AsSpan(0, length)) > budget)
+            {
+                length--;
+            }
+
+            // Never cut a surrogate pair in half, the lone half is not a valid file name character.
+            if (length > 0 && char.IsHighSurrogate(validName[length - 1]))
+            {
+                length--;
+            }
+
+            return string.Concat(validName.AsSpan(0, length).TrimEnd().TrimEnd('.'), suffix);
+        }
+
+        /// <summary>
         /// Cleans a raw name into its sortable form by applying the configured sort rules.
         /// </summary>
         /// <param name="name">The raw name to clean.</param>
diff --git a/MediaBrowser.Controller/Entities/Genre.cs b/MediaBrowser.Controller/Entities/Genre.cs
index 6ec78a270e..ef8acaef92 100644
--- a/MediaBrowser.Controller/Entities/Genre.cs
+++ b/MediaBrowser.Controller/Entities/Genre.cs
@@ -83,10 +83,7 @@ namespace MediaBrowser.Controller.Entities
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validName = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validName = normalizeName ? GetItemByNameFolderName(name) : name;
 
             return System.IO.Path.Combine(ConfigurationManager.ApplicationPaths.GenrePath, validName);
         }
diff --git a/MediaBrowser.Controller/Entities/Person.cs b/MediaBrowser.Controller/Entities/Person.cs
index 14325d971a..bba5005eed 100644
--- a/MediaBrowser.Controller/Entities/Person.cs
+++ b/MediaBrowser.Controller/Entities/Person.cs
@@ -98,10 +98,7 @@ namespace MediaBrowser.Controller.Entities
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validFilename = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validFilename = normalizeName ? GetItemByNameFolderName(name) : name;
 
             string subFolderPrefix = null;
 
diff --git a/MediaBrowser.Controller/Entities/Studio.cs b/MediaBrowser.Controller/Entities/Studio.cs
index 9103b09a95..a944b356c8 100644
--- a/MediaBrowser.Controller/Entities/Studio.cs
+++ b/MediaBrowser.Controller/Entities/Studio.cs
@@ -78,10 +78,7 @@ namespace MediaBrowser.Controller.Entities
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validName = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validName = normalizeName ? GetItemByNameFolderName(name) : name;
 
             return System.IO.Path.Combine(ConfigurationManager.ApplicationPaths.StudioPath, validName);
         }
diff --git a/MediaBrowser.Controller/Entities/TV/Series.cs b/MediaBrowser.Controller/Entities/TV/Series.cs
index 3ce241aca8..1a1da84b7a 100644
--- a/MediaBrowser.Controller/Entities/TV/Series.cs
+++ b/MediaBrowser.Controller/Entities/TV/Series.cs
@@ -4,6 +4,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using System.Text.Json.Serialization;
 using System.Threading;
@@ -89,15 +90,14 @@ namespace MediaBrowser.Controller.Entities.TV
 
                 if (!string.IsNullOrEmpty(groupingKey))
                 {
-                    return AppendPreferredLanguage(groupingKey);
+                    return AddLibrariesToPresentationUniqueKey(groupingKey);
                 }
             }
 
             return base.CreatePresentationUniqueKey();
         }
 
-        // The owning libraries are deliberately NOT part of the key.
-        private string AppendPreferredLanguage(string key)
+        private string AddLibrariesToPresentationUniqueKey(string key)
         {
             var lang = GetPreferredMetadataLanguage();
             if (!string.IsNullOrEmpty(lang))
@@ -105,7 +105,17 @@ namespace MediaBrowser.Controller.Entities.TV
                 key += "-" + lang;
             }
 
-            return key;
+            var folders = LibraryManager.GetCollectionFolders(this)
+                .Select(i => i.Id.ToString("N", CultureInfo.InvariantCulture))
+                .Order(StringComparer.Ordinal)
+                .ToArray();
+
+            if (folders.Length == 0)
+            {
+                return key;
+            }
+
+            return key + "-" + string.Join('-', folders);
         }
 
         private string GetNameBasedGroupingKey()
@@ -125,20 +135,19 @@ namespace MediaBrowser.Controller.Entities.TV
         {
             var seriesKey = GetUniqueSeriesKey(this);
 
-            var result = LibraryManager.GetCount(new InternalItemsQuery(user)
+            var result = LibraryManager.GetItemIds(new InternalItemsQuery(user)
             {
                 AncestorWithPresentationUniqueKey = null,
                 SeriesPresentationUniqueKey = seriesKey,
                 IncludeItemTypes = new[] { BaseItemKind.Season },
                 IsVirtualItem = false,
-                Limit = 0,
                 DtoOptions = new DtoOptions(false)
                 {
                     EnableImages = false
                 }
             });
 
-            return result;
+            return result.Count;
         }
 
         public override int GetRecursiveChildCount(User user)
diff --git a/MediaBrowser.Controller/Entities/Year.cs b/MediaBrowser.Controller/Entities/Year.cs
index 37820296cc..03fb2156d3 100644
--- a/MediaBrowser.Controller/Entities/Year.cs
+++ b/MediaBrowser.Controller/Entities/Year.cs
@@ -85,10 +85,7 @@ namespace MediaBrowser.Controller.Entities
 
         public static string GetPath(string name, bool normalizeName)
         {
-            // Trim the period at the end because windows will have a hard time with that
-            var validName = normalizeName ?
-                FileSystem.GetValidFilename(name).Trim().TrimEnd('.') :
-                name;
+            var validName = normalizeName ? GetItemByNameFolderName(name) : name;
 
             return System.IO.Path.Combine(ConfigurationManager.ApplicationPaths.YearPath, validName);
         }